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  # contributor license agreements.  See the NOTICE file distributed with
  # this work for additional information regarding copyright ownership.
  # The ASF licenses this file to You under the Apache License, Version 2.0
  # (the "License"); you may not use this file except in compliance with
  # the License.  You may obtain a copy of the License at
  #
  #    http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  #
  
  import unittest
  import inspect
  from distutils.version import LooseVersion
  from itertools import product
  
  import numpy as np
  import pandas as pd
  
  from pyspark import pandas as ps
  from pyspark.pandas.config import option_context
  from pyspark.pandas.exceptions import PandasNotImplementedError, DataError
  from pyspark.pandas.missing.groupby import (
      MissingPandasLikeDataFrameGroupBy,
      MissingPandasLikeSeriesGroupBy,
  )
  from pyspark.pandas.groupby import is_multi_agg_with_relabel
  from pyspark.testing.pandasutils import PandasOnSparkTestCase, TestUtils
  
  
  class GroupByTest(PandasOnSparkTestCase, TestUtils):
      def test_groupby_simple(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 2, 6, 4, 4, 6, 4, 3, 7],
                  "b": [4, 2, 7, 3, 3, 1, 1, 1, 2],
                  "c": [4, 2, 7, 3, None, 1, 1, 1, 2],
                  "d": list("abcdefght"),
              },
              index=[0, 1, 3, 5, 6, 8, 9, 9, 9],
          )
          psdf = ps.from_pandas(pdf)
  
          for as_index in [True, False]:
              if as_index:
                  sort = lambda df: df.sort_index()
              else:
                  sort = lambda df: df.sort_values("a").reset_index(drop=True)
              self.assert_eq(
                  sort(psdf.groupby("a", as_index=as_index).sum()),
                  sort(pdf.groupby("a", as_index=as_index).sum()),
              )
              self.assert_eq(
                  sort(psdf.groupby("a", as_index=as_index).b.sum()),
                  sort(pdf.groupby("a", as_index=as_index).b.sum()),
              )
              self.assert_eq(
                  sort(psdf.groupby("a", as_index=as_index)["b"].sum()),
                  sort(pdf.groupby("a", as_index=as_index)["b"].sum()),
              )
              self.assert_eq(
                  sort(psdf.groupby("a", as_index=as_index)[["b", "c"]].sum()),
                  sort(pdf.groupby("a", as_index=as_index)[["b", "c"]].sum()),
              )
              self.assert_eq(
                  sort(psdf.groupby("a", as_index=as_index)[[]].sum()),
                  sort(pdf.groupby("a", as_index=as_index)[[]].sum()),
              )
              self.assert_eq(
                  sort(psdf.groupby("a", as_index=as_index)["c"].sum()),
                  sort(pdf.groupby("a", as_index=as_index)["c"].sum()),
              )
  
          self.assert_eq(
              psdf.groupby("a").a.sum().sort_index(), pdf.groupby("a").a.sum().sort_index()
          )
          self.assert_eq(
              psdf.groupby("a")["a"].sum().sort_index(), pdf.groupby("a")["a"].sum().sort_index()
          )
          self.assert_eq(
              psdf.groupby("a")[["a"]].sum().sort_index(), pdf.groupby("a")[["a"]].sum().sort_index()
          )
          self.assert_eq(
              psdf.groupby("a")[["a", "c"]].sum().sort_index(),
              pdf.groupby("a")[["a", "c"]].sum().sort_index(),
          )
  
          self.assert_eq(
              psdf.a.groupby(psdf.b).sum().sort_index(), pdf.a.groupby(pdf.b).sum().sort_index()
          )
  
          for axis in [0, "index"]:
              self.assert_eq(
                  psdf.groupby("a", axis=axis).a.sum().sort_index(),
                  pdf.groupby("a", axis=axis).a.sum().sort_index(),
              )
              self.assert_eq(
                  psdf.groupby("a", axis=axis)["a"].sum().sort_index(),
                  pdf.groupby("a", axis=axis)["a"].sum().sort_index(),
              )
              self.assert_eq(
                  psdf.groupby("a", axis=axis)[["a"]].sum().sort_index(),
                  pdf.groupby("a", axis=axis)[["a"]].sum().sort_index(),
              )
              self.assert_eq(
                  psdf.groupby("a", axis=axis)[["a", "c"]].sum().sort_index(),
                  pdf.groupby("a", axis=axis)[["a", "c"]].sum().sort_index(),
              )
  
              self.assert_eq(
                  psdf.a.groupby(psdf.b, axis=axis).sum().sort_index(),
                  pdf.a.groupby(pdf.b, axis=axis).sum().sort_index(),
              )
  
          self.assertRaises(ValueError, lambda: psdf.groupby("a", as_index=False).a)
          self.assertRaises(ValueError, lambda: psdf.groupby("a", as_index=False)["a"])
          self.assertRaises(ValueError, lambda: psdf.groupby("a", as_index=False)[["a"]])
          self.assertRaises(ValueError, lambda: psdf.groupby("a", as_index=False)[["a", "c"]])
          self.assertRaises(KeyError, lambda: psdf.groupby("z", as_index=False)[["a", "c"]])
          self.assertRaises(KeyError, lambda: psdf.groupby(["z"], as_index=False)[["a", "c"]])
  
          self.assertRaises(TypeError, lambda: psdf.a.groupby(psdf.b, as_index=False))
  
          self.assertRaises(NotImplementedError, lambda: psdf.groupby("a", axis=1))
          self.assertRaises(NotImplementedError, lambda: psdf.groupby("a", axis="columns"))
          self.assertRaises(ValueError, lambda: psdf.groupby("a", "b"))
          self.assertRaises(TypeError, lambda: psdf.a.groupby(psdf.a, psdf.b))
  
          # we can't use column name/names as a parameter `by` for `SeriesGroupBy`.
          self.assertRaises(KeyError, lambda: psdf.a.groupby(by="a"))
          self.assertRaises(KeyError, lambda: psdf.a.groupby(by=["a", "b"]))
          self.assertRaises(KeyError, lambda: psdf.a.groupby(by=("a", "b")))
  
          # we can't use DataFrame as a parameter `by` for `DataFrameGroupBy`/`SeriesGroupBy`.
          self.assertRaises(ValueError, lambda: psdf.groupby(psdf))
          self.assertRaises(ValueError, lambda: psdf.a.groupby(psdf))
          self.assertRaises(ValueError, lambda: psdf.a.groupby((psdf,)))
  
          # non-string names
          pdf = pd.DataFrame(
              {
                  10: [1, 2, 6, 4, 4, 6, 4, 3, 7],
                  20: [4, 2, 7, 3, 3, 1, 1, 1, 2],
                  30: [4, 2, 7, 3, None, 1, 1, 1, 2],
                  40: list("abcdefght"),
              },
              index=[0, 1, 3, 5, 6, 8, 9, 9, 9],
          )
          psdf = ps.from_pandas(pdf)
  
          for as_index in [True, False]:
              if as_index:
                  sort = lambda df: df.sort_index()
              else:
                  sort = lambda df: df.sort_values(10).reset_index(drop=True)
              self.assert_eq(
                  sort(psdf.groupby(10, as_index=as_index).sum()),
                  sort(pdf.groupby(10, as_index=as_index).sum()),
              )
              self.assert_eq(
                  sort(psdf.groupby(10, as_index=as_index)[20].sum()),
                  sort(pdf.groupby(10, as_index=as_index)[20].sum()),
              )
              self.assert_eq(
                  sort(psdf.groupby(10, as_index=as_index)[[20, 30]].sum()),
                  sort(pdf.groupby(10, as_index=as_index)[[20, 30]].sum()),
              )
  
      def test_groupby_multiindex_columns(self):
          pdf = pd.DataFrame(
              {
                  (10, "a"): [1, 2, 6, 4, 4, 6, 4, 3, 7],
                  (10, "b"): [4, 2, 7, 3, 3, 1, 1, 1, 2],
                  (20, "c"): [4, 2, 7, 3, None, 1, 1, 1, 2],
                  (30, "d"): list("abcdefght"),
              },
              index=[0, 1, 3, 5, 6, 8, 9, 9, 9],
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              psdf.groupby((10, "a")).sum().sort_index(), pdf.groupby((10, "a")).sum().sort_index()
          )
          self.assert_eq(
              psdf.groupby((10, "a"), as_index=False)
              .sum()
              .sort_values((10, "a"))
              .reset_index(drop=True),
              pdf.groupby((10, "a"), as_index=False)
              .sum()
              .sort_values((10, "a"))
              .reset_index(drop=True),
          )
          self.assert_eq(
              psdf.groupby((10, "a"))[[(20, "c")]].sum().sort_index(),
              pdf.groupby((10, "a"))[[(20, "c")]].sum().sort_index(),
          )
  
          # TODO: a pandas bug?
          #  expected = pdf.groupby((10, "a"))[(20, "c")].sum().sort_index()
          expected = pd.Series(
              [4.0, 2.0, 1.0, 4.0, 8.0, 2.0],
              name=(20, "c"),
              index=pd.Index([1, 2, 3, 4, 6, 7], name=(10, "a")),
          )
  
          self.assert_eq(psdf.groupby((10, "a"))[(20, "c")].sum().sort_index(), expected)
  
          if (
              LooseVersion(pd.__version__) >= LooseVersion("1.0.4")
              and LooseVersion(pd.__version__) != LooseVersion("1.1.3")
              and LooseVersion(pd.__version__) != LooseVersion("1.1.4")
          ):
              self.assert_eq(
                  psdf[(20, "c")].groupby(psdf[(10, "a")]).sum().sort_index(),
                  pdf[(20, "c")].groupby(pdf[(10, "a")]).sum().sort_index(),
              )
          else:
              # Due to pandas bugs resolved in 1.0.4, re-introduced in 1.1.3 and resolved in 1.1.5
              self.assert_eq(psdf[(20, "c")].groupby(psdf[(10, "a")]).sum().sort_index(), expected)
  
      def test_split_apply_combine_on_series(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 2, 6, 4, 4, 6, 4, 3, 7],
                  "b": [4, 2, 7, 3, 3, 1, 1, 1, 2],
                  "c": [4, 2, 7, 3, None, 1, 1, 1, 2],
                  "d": list("abcdefght"),
              },
              index=[0, 1, 3, 5, 6, 8, 9, 9, 9],
          )
          psdf = ps.from_pandas(pdf)
  
          funcs = [
              ((True, False), ["sum", "min", "max", "count", "first", "last"]),
              ((True, True), ["mean"]),
              ((False, False), ["var", "std"]),
          ]
          funcs = [(check_exact, almost, f) for (check_exact, almost), fs in funcs for f in fs]
  
          for as_index in [True, False]:
              if as_index:
                  sort = lambda df: df.sort_index()
              else:
                  sort = lambda df: df.sort_values(list(df.columns)).reset_index(drop=True)
  
              for check_exact, almost, func in funcs:
                  for kkey, pkey in [("b", "b"), (psdf.b, pdf.b)]:
                      with self.subTest(as_index=as_index, func=func, key=pkey):
                          if as_index is True or func != "std":
                              self.assert_eq(
                                  sort(getattr(psdf.groupby(kkey, as_index=as_index).a, func)()),
                                  sort(getattr(pdf.groupby(pkey, as_index=as_index).a, func)()),
                                  check_exact=check_exact,
                                  almost=almost,
                              )
                              self.assert_eq(
                                  sort(getattr(psdf.groupby(kkey, as_index=as_index), func)()),
                                  sort(getattr(pdf.groupby(pkey, as_index=as_index), func)()),
                                  check_exact=check_exact,
                                  almost=almost,
                              )
                          else:
                              # seems like a pandas' bug for as_index=False and func == "std"?
                              self.assert_eq(
                                  sort(getattr(psdf.groupby(kkey, as_index=as_index).a, func)()),
                                  sort(pdf.groupby(pkey, as_index=True).a.std().reset_index()),
                                  check_exact=check_exact,
                                  almost=almost,
                              )
                              self.assert_eq(
                                  sort(getattr(psdf.groupby(kkey, as_index=as_index), func)()),
                                  sort(pdf.groupby(pkey, as_index=True).std().reset_index()),
                                  check_exact=check_exact,
                                  almost=almost,
                              )
  
                  for kkey, pkey in [(psdf.b + 1, pdf.b + 1), (psdf.copy().b, pdf.copy().b)]:
                      with self.subTest(as_index=as_index, func=func, key=pkey):
                          self.assert_eq(
                              sort(getattr(psdf.groupby(kkey, as_index=as_index).a, func)()),
                              sort(getattr(pdf.groupby(pkey, as_index=as_index).a, func)()),
                              check_exact=check_exact,
                              almost=almost,
                          )
                          self.assert_eq(
                              sort(getattr(psdf.groupby(kkey, as_index=as_index), func)()),
                              sort(getattr(pdf.groupby(pkey, as_index=as_index), func)()),
                              check_exact=check_exact,
                              almost=almost,
                          )
  
              for check_exact, almost, func in funcs:
                  for i in [0, 4, 7]:
                      with self.subTest(as_index=as_index, func=func, i=i):
                          self.assert_eq(
                              sort(getattr(psdf.groupby(psdf.b > i, as_index=as_index).a, func)()),
                              sort(getattr(pdf.groupby(pdf.b > i, as_index=as_index).a, func)()),
                              check_exact=check_exact,
                              almost=almost,
                          )
                          self.assert_eq(
                              sort(getattr(psdf.groupby(psdf.b > i, as_index=as_index), func)()),
                              sort(getattr(pdf.groupby(pdf.b > i, as_index=as_index), func)()),
                              check_exact=check_exact,
                              almost=almost,
                          )
  
          for check_exact, almost, func in funcs:
              for kkey, pkey in [
                  (psdf.b, pdf.b),
                  (psdf.b + 1, pdf.b + 1),
                  (psdf.copy().b, pdf.copy().b),
                  (psdf.b.rename(), pdf.b.rename()),
              ]:
                  with self.subTest(func=func, key=pkey):
                      self.assert_eq(
                          getattr(psdf.a.groupby(kkey), func)().sort_index(),
                          getattr(pdf.a.groupby(pkey), func)().sort_index(),
                          check_exact=check_exact,
                          almost=almost,
                      )
                      self.assert_eq(
                          getattr((psdf.a + 1).groupby(kkey), func)().sort_index(),
                          getattr((pdf.a + 1).groupby(pkey), func)().sort_index(),
                          check_exact=check_exact,
                          almost=almost,
                      )
                      self.assert_eq(
                          getattr((psdf.b + 1).groupby(kkey), func)().sort_index(),
                          getattr((pdf.b + 1).groupby(pkey), func)().sort_index(),
                          check_exact=check_exact,
                          almost=almost,
                      )
                      self.assert_eq(
                          getattr(psdf.a.rename().groupby(kkey), func)().sort_index(),
                          getattr(pdf.a.rename().groupby(pkey), func)().sort_index(),
                          check_exact=check_exact,
                          almost=almost,
                      )
  
      def test_aggregate(self):
          pdf = pd.DataFrame(
              {"A": [1, 1, 2, 2], "B": [1, 2, 3, 4], "C": [0.362, 0.227, 1.267, -0.562]}
          )
          psdf = ps.from_pandas(pdf)
  
          for as_index in [True, False]:
              if as_index:
                  sort = lambda df: df.sort_index()
              else:
                  sort = lambda df: df.sort_values(list(df.columns)).reset_index(drop=True)
  
              for kkey, pkey in [("A", "A"), (psdf.A, pdf.A)]:
                  with self.subTest(as_index=as_index, key=pkey):
                      self.assert_eq(
                          sort(psdf.groupby(kkey, as_index=as_index).agg("sum")),
                          sort(pdf.groupby(pkey, as_index=as_index).agg("sum")),
                      )
                      self.assert_eq(
                          sort(psdf.groupby(kkey, as_index=as_index).agg({"B": "min", "C": "sum"})),
                          sort(pdf.groupby(pkey, as_index=as_index).agg({"B": "min", "C": "sum"})),
                      )
                      self.assert_eq(
                          sort(
                              psdf.groupby(kkey, as_index=as_index).agg(
                                  {"B": ["min", "max"], "C": "sum"}
                              )
                          ),
                          sort(
                              pdf.groupby(pkey, as_index=as_index).agg(
                                  {"B": ["min", "max"], "C": "sum"}
                              )
                          ),
                      )
  
                      if as_index:
                          self.assert_eq(
                              sort(psdf.groupby(kkey, as_index=as_index).agg(["sum"])),
                              sort(pdf.groupby(pkey, as_index=as_index).agg(["sum"])),
                          )
                      else:
                          # seems like a pandas' bug for as_index=False and func_or_funcs is list?
                          self.assert_eq(
                              sort(psdf.groupby(kkey, as_index=as_index).agg(["sum"])),
                              sort(pdf.groupby(pkey, as_index=True).agg(["sum"]).reset_index()),
                          )
  
              for kkey, pkey in [(psdf.A + 1, pdf.A + 1), (psdf.copy().A, pdf.copy().A)]:
                  with self.subTest(as_index=as_index, key=pkey):
                      self.assert_eq(
                          sort(psdf.groupby(kkey, as_index=as_index).agg("sum")),
                          sort(pdf.groupby(pkey, as_index=as_index).agg("sum")),
                      )
                      self.assert_eq(
                          sort(psdf.groupby(kkey, as_index=as_index).agg({"B": "min", "C": "sum"})),
                          sort(pdf.groupby(pkey, as_index=as_index).agg({"B": "min", "C": "sum"})),
                      )
                      self.assert_eq(
                          sort(
                              psdf.groupby(kkey, as_index=as_index).agg(
                                  {"B": ["min", "max"], "C": "sum"}
                              )
                          ),
                          sort(
                              pdf.groupby(pkey, as_index=as_index).agg(
                                  {"B": ["min", "max"], "C": "sum"}
                              )
                          ),
                      )
                      self.assert_eq(
                          sort(psdf.groupby(kkey, as_index=as_index).agg(["sum"])),
                          sort(pdf.groupby(pkey, as_index=as_index).agg(["sum"])),
                      )
  
          expected_error_message = (
              r"aggs must be a dict mapping from column name to aggregate functions "
              r"\(string or list of strings\)."
          )
          with self.assertRaisesRegex(ValueError, expected_error_message):
              psdf.groupby("A", as_index=as_index).agg(0)
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([(10, "A"), (10, "B"), (20, "C")])
          pdf.columns = columns
          psdf.columns = columns
  
          for as_index in [True, False]:
              stats_psdf = psdf.groupby((10, "A"), as_index=as_index).agg(
                  {(10, "B"): "min", (20, "C"): "sum"}
              )
              stats_pdf = pdf.groupby((10, "A"), as_index=as_index).agg(
                  {(10, "B"): "min", (20, "C"): "sum"}
              )
              self.assert_eq(
                  stats_psdf.sort_values(by=[(10, "B"), (20, "C")]).reset_index(drop=True),
                  stats_pdf.sort_values(by=[(10, "B"), (20, "C")]).reset_index(drop=True),
              )
  
          stats_psdf = psdf.groupby((10, "A")).agg({(10, "B"): ["min", "max"], (20, "C"): "sum"})
          stats_pdf = pdf.groupby((10, "A")).agg({(10, "B"): ["min", "max"], (20, "C"): "sum"})
          self.assert_eq(
              stats_psdf.sort_values(
                  by=[(10, "B", "min"), (10, "B", "max"), (20, "C", "sum")]
              ).reset_index(drop=True),
              stats_pdf.sort_values(
                  by=[(10, "B", "min"), (10, "B", "max"), (20, "C", "sum")]
              ).reset_index(drop=True),
          )
  
          # non-string names
          pdf.columns = [10, 20, 30]
          psdf.columns = [10, 20, 30]
  
          for as_index in [True, False]:
              stats_psdf = psdf.groupby(10, as_index=as_index).agg({20: "min", 30: "sum"})
              stats_pdf = pdf.groupby(10, as_index=as_index).agg({20: "min", 30: "sum"})
              self.assert_eq(
                  stats_psdf.sort_values(by=[20, 30]).reset_index(drop=True),
                  stats_pdf.sort_values(by=[20, 30]).reset_index(drop=True),
              )
  
          stats_psdf = psdf.groupby(10).agg({20: ["min", "max"], 30: "sum"})
          stats_pdf = pdf.groupby(10).agg({20: ["min", "max"], 30: "sum"})
          self.assert_eq(
              stats_psdf.sort_values(by=[(20, "min"), (20, "max"), (30, "sum")]).reset_index(
                  drop=True
              ),
              stats_pdf.sort_values(by=[(20, "min"), (20, "max"), (30, "sum")]).reset_index(
                  drop=True
              ),
          )
  
      def test_aggregate_func_str_list(self):
          # this is test for cases where only string or list is assigned
          pdf = pd.DataFrame(
              {
                  "kind": ["cat", "dog", "cat", "dog"],
                  "height": [9.1, 6.0, 9.5, 34.0],
                  "weight": [7.9, 7.5, 9.9, 198.0],
              }
          )
          psdf = ps.from_pandas(pdf)
  
          agg_funcs = ["max", "min", ["min", "max"]]
          for aggfunc in agg_funcs:
  
              # Since in Koalas groupby, the order of rows might be different
              # so sort on index to ensure they have same output
              sorted_agg_psdf = psdf.groupby("kind").agg(aggfunc).sort_index()
              sorted_agg_pdf = pdf.groupby("kind").agg(aggfunc).sort_index()
              self.assert_eq(sorted_agg_psdf, sorted_agg_pdf)
  
          # test on multi index column case
          pdf = pd.DataFrame(
              {"A": [1, 1, 2, 2], "B": [1, 2, 3, 4], "C": [0.362, 0.227, 1.267, -0.562]}
          )
          psdf = ps.from_pandas(pdf)
  
          columns = pd.MultiIndex.from_tuples([("X", "A"), ("X", "B"), ("Y", "C")])
          pdf.columns = columns
          psdf.columns = columns
  
          for aggfunc in agg_funcs:
              sorted_agg_psdf = psdf.groupby(("X", "A")).agg(aggfunc).sort_index()
              sorted_agg_pdf = pdf.groupby(("X", "A")).agg(aggfunc).sort_index()
              self.assert_eq(sorted_agg_psdf, sorted_agg_pdf)
  
      @unittest.skipIf(pd.__version__ < "0.25.0", "not supported before pandas 0.25.0")
      def test_aggregate_relabel(self):
          # this is to test named aggregation in groupby
          pdf = pd.DataFrame({"group": ["a", "a", "b", "b"], "A": [0, 1, 2, 3], "B": [5, 6, 7, 8]})
          psdf = ps.from_pandas(pdf)
  
          # different agg column, same function
          agg_pdf = pdf.groupby("group").agg(a_max=("A", "max"), b_max=("B", "max")).sort_index()
          agg_psdf = psdf.groupby("group").agg(a_max=("A", "max"), b_max=("B", "max")).sort_index()
          self.assert_eq(agg_pdf, agg_psdf)
  
          # same agg column, different functions
          agg_pdf = pdf.groupby("group").agg(b_max=("B", "max"), b_min=("B", "min")).sort_index()
          agg_psdf = psdf.groupby("group").agg(b_max=("B", "max"), b_min=("B", "min")).sort_index()
          self.assert_eq(agg_pdf, agg_psdf)
  
          # test on NamedAgg
          agg_pdf = (
              pdf.groupby("group").agg(b_max=pd.NamedAgg(column="B", aggfunc="max")).sort_index()
          )
          agg_psdf = (
              psdf.groupby("group").agg(b_max=ps.NamedAgg(column="B", aggfunc="max")).sort_index()
          )
          self.assert_eq(agg_psdf, agg_pdf)
  
          # test on NamedAgg multi columns aggregation
          agg_pdf = (
              pdf.groupby("group")
              .agg(
                  b_max=pd.NamedAgg(column="B", aggfunc="max"),
                  b_min=pd.NamedAgg(column="B", aggfunc="min"),
              )
              .sort_index()
          )
          agg_psdf = (
              psdf.groupby("group")
              .agg(
                  b_max=ps.NamedAgg(column="B", aggfunc="max"),
                  b_min=ps.NamedAgg(column="B", aggfunc="min"),
              )
              .sort_index()
          )
          self.assert_eq(agg_psdf, agg_pdf)
  
      def test_dropna(self):
          pdf = pd.DataFrame(
              {"A": [None, 1, None, 1, 2], "B": [1, 2, 3, None, None], "C": [4, 5, 6, 7, None]}
          )
          psdf = ps.from_pandas(pdf)
  
          # pd.DataFrame.groupby with dropna parameter is implemented since pandas 1.1.0
          if LooseVersion(pd.__version__) >= LooseVersion("1.1.0"):
              for dropna in [True, False]:
                  for as_index in [True, False]:
                      if as_index:
                          sort = lambda df: df.sort_index()
                      else:
                          sort = lambda df: df.sort_values("A").reset_index(drop=True)
  
                      self.assert_eq(
                          sort(psdf.groupby("A", as_index=as_index, dropna=dropna).std()),
                          sort(pdf.groupby("A", as_index=as_index, dropna=dropna).std()),
                      )
  
                      self.assert_eq(
                          sort(psdf.groupby("A", as_index=as_index, dropna=dropna).B.std()),
                          sort(pdf.groupby("A", as_index=as_index, dropna=dropna).B.std()),
                      )
                      self.assert_eq(
                          sort(psdf.groupby("A", as_index=as_index, dropna=dropna)["B"].std()),
                          sort(pdf.groupby("A", as_index=as_index, dropna=dropna)["B"].std()),
                      )
  
                      self.assert_eq(
                          sort(
                              psdf.groupby("A", as_index=as_index, dropna=dropna).agg(
                                  {"B": "min", "C": "std"}
                              )
                          ),
                          sort(
                              pdf.groupby("A", as_index=as_index, dropna=dropna).agg(
                                  {"B": "min", "C": "std"}
                              )
                          ),
                      )
  
              for dropna in [True, False]:
                  for as_index in [True, False]:
                      if as_index:
                          sort = lambda df: df.sort_index()
                      else:
                          sort = lambda df: df.sort_values(["A", "B"]).reset_index(drop=True)
  
                      self.assert_eq(
                          sort(
                              psdf.groupby(["A", "B"], as_index=as_index, dropna=dropna).agg(
                                  {"C": ["min", "std"]}
                              )
                          ),
                          sort(
                              pdf.groupby(["A", "B"], as_index=as_index, dropna=dropna).agg(
                                  {"C": ["min", "std"]}
                              )
                          ),
                          almost=True,
                      )
  
              # multi-index columns
              columns = pd.MultiIndex.from_tuples([("X", "A"), ("X", "B"), ("Y", "C")])
              pdf.columns = columns
              psdf.columns = columns
  
              for dropna in [True, False]:
                  for as_index in [True, False]:
                      if as_index:
                          sort = lambda df: df.sort_index()
                      else:
                          sort = lambda df: df.sort_values(("X", "A")).reset_index(drop=True)
                      sorted_stats_psdf = sort(
                          psdf.groupby(("X", "A"), as_index=as_index, dropna=dropna).agg(
                              {("X", "B"): "min", ("Y", "C"): "std"}
                          )
                      )
                      sorted_stats_pdf = sort(
                          pdf.groupby(("X", "A"), as_index=as_index, dropna=dropna).agg(
                              {("X", "B"): "min", ("Y", "C"): "std"}
                          )
                      )
                      self.assert_eq(sorted_stats_psdf, sorted_stats_pdf)
          else:
              # Testing dropna=True (pandas default behavior)
              for as_index in [True, False]:
                  if as_index:
                      sort = lambda df: df.sort_index()
                  else:
                      sort = lambda df: df.sort_values("A").reset_index(drop=True)
  
                  self.assert_eq(
                      sort(psdf.groupby("A", as_index=as_index, dropna=True)["B"].min()),
                      sort(pdf.groupby("A", as_index=as_index)["B"].min()),
                  )
  
                  if as_index:
                      sort = lambda df: df.sort_index()
                  else:
                      sort = lambda df: df.sort_values(["A", "B"]).reset_index(drop=True)
  
                  self.assert_eq(
                      sort(
                          psdf.groupby(["A", "B"], as_index=as_index, dropna=True).agg(
                              {"C": ["min", "std"]}
                          )
                      ),
                      sort(pdf.groupby(["A", "B"], as_index=as_index).agg({"C": ["min", "std"]})),
                      almost=True,
                  )
  
              # Testing dropna=False
              index = pd.Index([1.0, 2.0, np.nan], name="A")
              expected = pd.Series([2.0, np.nan, 1.0], index=index, name="B")
              result = psdf.groupby("A", as_index=True, dropna=False)["B"].min().sort_index()
              self.assert_eq(expected, result)
  
              expected = pd.DataFrame({"A": [1.0, 2.0, np.nan], "B": [2.0, np.nan, 1.0]})
              result = (
                  psdf.groupby("A", as_index=False, dropna=False)["B"]
                  .min()
                  .sort_values("A")
                  .reset_index(drop=True)
              )
              self.assert_eq(expected, result)
  
              index = pd.MultiIndex.from_tuples(
                  [(1.0, 2.0), (1.0, None), (2.0, None), (None, 1.0), (None, 3.0)], names=["A", "B"]
              )
              expected = pd.DataFrame(
                  {
                      ("C", "min"): [5.0, 7.0, np.nan, 4.0, 6.0],
                      ("C", "std"): [np.nan, np.nan, np.nan, np.nan, np.nan],
                  },
                  index=index,
              )
              result = (
                  psdf.groupby(["A", "B"], as_index=True, dropna=False)
                  .agg({"C": ["min", "std"]})
                  .sort_index()
              )
              self.assert_eq(expected, result)
  
              expected = pd.DataFrame(
                  {
                      ("A", ""): [1.0, 1.0, 2.0, np.nan, np.nan],
                      ("B", ""): [2.0, np.nan, np.nan, 1.0, 3.0],
                      ("C", "min"): [5.0, 7.0, np.nan, 4.0, 6.0],
                      ("C", "std"): [np.nan, np.nan, np.nan, np.nan, np.nan],
                  }
              )
              result = (
                  psdf.groupby(["A", "B"], as_index=False, dropna=False)
                  .agg({"C": ["min", "std"]})
                  .sort_values(["A", "B"])
                  .reset_index(drop=True)
              )
              self.assert_eq(expected, result)
  
      def test_describe(self):
          # support for numeric type, not support for string type yet
          datas = []
          datas.append({"a": [1, 1, 3], "b": [4, 5, 6], "c": [7, 8, 9]})
          datas.append({"a": [-1, -1, -3], "b": [-4, -5, -6], "c": [-7, -8, -9]})
          datas.append({"a": [0, 0, 0], "b": [0, 0, 0], "c": [0, 8, 0]})
          # it is okay if string type column as a group key
          datas.append({"a": ["a", "a", "c"], "b": [4, 5, 6], "c": [7, 8, 9]})
  
          percentiles = [0.25, 0.5, 0.75]
          formatted_percentiles = ["25%", "50%", "75%"]
          non_percentile_stats = ["count", "mean", "std", "min", "max"]
  
          for data in datas:
              pdf = pd.DataFrame(data)
              psdf = ps.from_pandas(pdf)
  
              describe_pdf = pdf.groupby("a").describe().sort_index()
              describe_psdf = psdf.groupby("a").describe().sort_index()
  
              # since the result of percentile columns are slightly difference from pandas,
              # we should check them separately: non-percentile columns & percentile columns
  
              # 1. Check that non-percentile columns are equal.
              agg_cols = [col.name for col in psdf.groupby("a")._agg_columns]
              self.assert_eq(
                  describe_psdf.drop(list(product(agg_cols, formatted_percentiles))),
                  describe_pdf.drop(columns=formatted_percentiles, level=1),
                  check_exact=False,
              )
  
              # 2. Check that percentile columns are equal.
              # The interpolation argument is yet to be implemented in Koalas.
              quantile_pdf = pdf.groupby("a").quantile(percentiles, interpolation="nearest")
              quantile_pdf = quantile_pdf.unstack(level=1).astype(float)
              self.assert_eq(
                  describe_psdf.drop(list(product(agg_cols, non_percentile_stats))),
                  quantile_pdf.rename(columns="{:.0%}".format, level=1),
              )
  
          # not support for string type yet
          datas = []
          datas.append({"a": ["a", "a", "c"], "b": ["d", "e", "f"], "c": ["g", "h", "i"]})
          datas.append({"a": ["a", "a", "c"], "b": [4, 0, 1], "c": ["g", "h", "i"]})
          for data in datas:
              pdf = pd.DataFrame(data)
              psdf = ps.from_pandas(pdf)
  
              self.assertRaises(
                  NotImplementedError, lambda: psdf.groupby("a").describe().sort_index()
              )
  
          # multi-index columns
          pdf = pd.DataFrame({("x", "a"): [1, 1, 3], ("x", "b"): [4, 5, 6], ("y", "c"): [7, 8, 9]})
          psdf = ps.from_pandas(pdf)
  
          describe_pdf = pdf.groupby(("x", "a")).describe().sort_index()
          describe_psdf = psdf.groupby(("x", "a")).describe().sort_index()
  
          # 1. Check that non-percentile columns are equal.
          agg_column_labels = [col._column_label for col in psdf.groupby(("x", "a"))._agg_columns]
          self.assert_eq(
              describe_psdf.drop(
                  [
                      tuple(list(label) + [s])
                      for label, s in product(agg_column_labels, formatted_percentiles)
                  ]
              ),
              describe_pdf.drop(columns=formatted_percentiles, level=2),
              check_exact=False,
          )
  
          # 2. Check that percentile columns are equal.
          # The interpolation argument is yet to be implemented in Koalas.
          quantile_pdf = pdf.groupby(("x", "a")).quantile(percentiles, interpolation="nearest")
          quantile_pdf = quantile_pdf.unstack(level=1).astype(float)
  
          self.assert_eq(
              describe_psdf.drop(
                  [
                      tuple(list(label) + [s])
                      for label, s in product(agg_column_labels, non_percentile_stats)
                  ]
              ),
              quantile_pdf.rename(columns="{:.0%}".format, level=2),
          )
  
      def test_aggregate_relabel_multiindex(self):
          pdf = pd.DataFrame({"A": [0, 1, 2, 3], "B": [5, 6, 7, 8], "group": ["a", "a", "b", "b"]})
          pdf.columns = pd.MultiIndex.from_tuples([("y", "A"), ("y", "B"), ("x", "group")])
          psdf = ps.from_pandas(pdf)
  
          if LooseVersion(pd.__version__) < LooseVersion("1.0.0"):
              agg_pdf = pd.DataFrame(
                  {"a_max": [1, 3]}, index=pd.Index(["a", "b"], name=("x", "group"))
              )
          elif LooseVersion(pd.__version__) >= LooseVersion("1.0.0"):
              agg_pdf = pdf.groupby(("x", "group")).agg(a_max=(("y", "A"), "max")).sort_index()
          agg_psdf = psdf.groupby(("x", "group")).agg(a_max=(("y", "A"), "max")).sort_index()
          self.assert_eq(agg_pdf, agg_psdf)
  
          # same column, different methods
          if LooseVersion(pd.__version__) < LooseVersion("1.0.0"):
              agg_pdf = pd.DataFrame(
                  {"a_max": [1, 3], "a_min": [0, 2]}, index=pd.Index(["a", "b"], name=("x", "group"))
              )
          elif LooseVersion(pd.__version__) >= LooseVersion("1.0.0"):
              agg_pdf = (
                  pdf.groupby(("x", "group"))
                  .agg(a_max=(("y", "A"), "max"), a_min=(("y", "A"), "min"))
                  .sort_index()
              )
          agg_psdf = (
              psdf.groupby(("x", "group"))
              .agg(a_max=(("y", "A"), "max"), a_min=(("y", "A"), "min"))
              .sort_index()
          )
          self.assert_eq(agg_pdf, agg_psdf)
  
          # different column, different methods
          if LooseVersion(pd.__version__) < LooseVersion("1.0.0"):
              agg_pdf = pd.DataFrame(
                  {"a_max": [6, 8], "a_min": [0, 2]}, index=pd.Index(["a", "b"], name=("x", "group"))
              )
          elif LooseVersion(pd.__version__) >= LooseVersion("1.0.0"):
              agg_pdf = (
                  pdf.groupby(("x", "group"))
                  .agg(a_max=(("y", "B"), "max"), a_min=(("y", "A"), "min"))
                  .sort_index()
              )
          agg_psdf = (
              psdf.groupby(("x", "group"))
              .agg(a_max=(("y", "B"), "max"), a_min=(("y", "A"), "min"))
              .sort_index()
          )
          self.assert_eq(agg_pdf, agg_psdf)
  
      def test_all_any(self):
          pdf = pd.DataFrame(
              {
                  "A": [1, 1, 2, 2, 3, 3, 4, 4, 5, 5],
                  "B": [True, True, True, False, False, False, None, True, None, False],
              }
          )
          psdf = ps.from_pandas(pdf)
  
          for as_index in [True, False]:
              if as_index:
                  sort = lambda df: df.sort_index()
              else:
                  sort = lambda df: df.sort_values("A").reset_index(drop=True)
              self.assert_eq(
                  sort(psdf.groupby("A", as_index=as_index).all()),
                  sort(pdf.groupby("A", as_index=as_index).all()),
              )
              self.assert_eq(
                  sort(psdf.groupby("A", as_index=as_index).any()),
                  sort(pdf.groupby("A", as_index=as_index).any()),
              )
  
              self.assert_eq(
                  sort(psdf.groupby("A", as_index=as_index).all()).B,
                  sort(pdf.groupby("A", as_index=as_index).all()).B,
              )
              self.assert_eq(
                  sort(psdf.groupby("A", as_index=as_index).any()).B,
                  sort(pdf.groupby("A", as_index=as_index).any()).B,
              )
  
          self.assert_eq(
              psdf.B.groupby(psdf.A).all().sort_index(), pdf.B.groupby(pdf.A).all().sort_index()
          )
          self.assert_eq(
              psdf.B.groupby(psdf.A).any().sort_index(), pdf.B.groupby(pdf.A).any().sort_index()
          )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("X", "A"), ("Y", "B")])
          pdf.columns = columns
          psdf.columns = columns
  
          for as_index in [True, False]:
              if as_index:
                  sort = lambda df: df.sort_index()
              else:
                  sort = lambda df: df.sort_values(("X", "A")).reset_index(drop=True)
              self.assert_eq(
                  sort(psdf.groupby(("X", "A"), as_index=as_index).all()),
                  sort(pdf.groupby(("X", "A"), as_index=as_index).all()),
              )
              self.assert_eq(
                  sort(psdf.groupby(("X", "A"), as_index=as_index).any()),
                  sort(pdf.groupby(("X", "A"), as_index=as_index).any()),
              )
  
      def test_raises(self):
          psdf = ps.DataFrame(
              {"a": [1, 2, 6, 4, 4, 6, 4, 3, 7], "b": [4, 2, 7, 3, 3, 1, 1, 1, 2]},
              index=[0, 1, 3, 5, 6, 8, 9, 9, 9],
          )
          # test raises with incorrect key
          self.assertRaises(ValueError, lambda: psdf.groupby([]))
          self.assertRaises(KeyError, lambda: psdf.groupby("x"))
          self.assertRaises(KeyError, lambda: psdf.groupby(["a", "x"]))
          self.assertRaises(KeyError, lambda: psdf.groupby("a")["x"])
          self.assertRaises(KeyError, lambda: psdf.groupby("a")["b", "x"])
          self.assertRaises(KeyError, lambda: psdf.groupby("a")[["b", "x"]])
  
      def test_nunique(self):
          pdf = pd.DataFrame(
              {"a": [1, 1, 1, 1, 1, 0, 0, 0, 0, 0], "b": [2, 2, 2, 3, 3, 4, 4, 5, 5, 5]}
          )
          psdf = ps.from_pandas(pdf)
          self.assert_eq(
              psdf.groupby("a").agg({"b": "nunique"}).sort_index(),
              pdf.groupby("a").agg({"b": "nunique"}).sort_index(),
          )
          if LooseVersion(pd.__version__) < LooseVersion("1.1.0"):
              expected = ps.DataFrame({"b": [2, 2]}, index=pd.Index([0, 1], name="a"))
              self.assert_eq(psdf.groupby("a").nunique().sort_index(), expected)
              self.assert_eq(
                  psdf.groupby("a").nunique(dropna=False).sort_index(),
                  expected,
              )
          else:
              self.assert_eq(
                  psdf.groupby("a").nunique().sort_index(), pdf.groupby("a").nunique().sort_index()
              )
              self.assert_eq(
                  psdf.groupby("a").nunique(dropna=False).sort_index(),
                  pdf.groupby("a").nunique(dropna=False).sort_index(),
              )
          self.assert_eq(
              psdf.groupby("a")["b"].nunique().sort_index(),
              pdf.groupby("a")["b"].nunique().sort_index(),
          )
          self.assert_eq(
              psdf.groupby("a")["b"].nunique(dropna=False).sort_index(),
              pdf.groupby("a")["b"].nunique(dropna=False).sort_index(),
          )
  
          nunique_psdf = psdf.groupby("a", as_index=False).agg({"b": "nunique"})
          nunique_pdf = pdf.groupby("a", as_index=False).agg({"b": "nunique"})
          self.assert_eq(
              nunique_psdf.sort_values(["a", "b"]).reset_index(drop=True),
              nunique_pdf.sort_values(["a", "b"]).reset_index(drop=True),
          )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("y", "b")])
          pdf.columns = columns
          psdf.columns = columns
  
          if LooseVersion(pd.__version__) < LooseVersion("1.1.0"):
              expected = ps.DataFrame({("y", "b"): [2, 2]}, index=pd.Index([0, 1], name=("x", "a")))
              self.assert_eq(
                  psdf.groupby(("x", "a")).nunique().sort_index(),
                  expected,
              )
              self.assert_eq(
                  psdf.groupby(("x", "a")).nunique(dropna=False).sort_index(),
                  expected,
              )
          else:
              self.assert_eq(
                  psdf.groupby(("x", "a")).nunique().sort_index(),
                  pdf.groupby(("x", "a")).nunique().sort_index(),
              )
              self.assert_eq(
                  psdf.groupby(("x", "a")).nunique(dropna=False).sort_index(),
                  pdf.groupby(("x", "a")).nunique(dropna=False).sort_index(),
              )
  
      def test_unique(self):
          for pdf in [
              pd.DataFrame(
                  {"a": [1, 1, 1, 1, 1, 0, 0, 0, 0, 0], "b": [2, 2, 2, 3, 3, 4, 4, 5, 5, 5]}
              ),
              pd.DataFrame(
                  {
                      "a": [1, 1, 1, 1, 1, 0, 0, 0, 0, 0],
                      "b": ["w", "w", "w", "x", "x", "y", "y", "z", "z", "z"],
                  }
              ),
          ]:
              with self.subTest(pdf=pdf):
                  psdf = ps.from_pandas(pdf)
  
                  actual = psdf.groupby("a")["b"].unique().sort_index().to_pandas()
                  expect = pdf.groupby("a")["b"].unique().sort_index()
                  self.assert_eq(len(actual), len(expect))
                  for act, exp in zip(actual, expect):
                      self.assertTrue(sorted(act) == sorted(exp))
  
      def test_value_counts(self):
          pdf = pd.DataFrame({"A": [1, 2, 2, 3, 3, 3], "B": [1, 1, 2, 3, 3, 3]}, columns=["A", "B"])
          psdf = ps.from_pandas(pdf)
          self.assert_eq(
              psdf.groupby("A")["B"].value_counts().sort_index(),
              pdf.groupby("A")["B"].value_counts().sort_index(),
          )
          self.assert_eq(
              psdf.groupby("A")["B"].value_counts(sort=True, ascending=False).sort_index(),
              pdf.groupby("A")["B"].value_counts(sort=True, ascending=False).sort_index(),
          )
          self.assert_eq(
              psdf.groupby("A")["B"].value_counts(sort=True, ascending=True).sort_index(),
              pdf.groupby("A")["B"].value_counts(sort=True, ascending=True).sort_index(),
          )
          self.assert_eq(
              psdf.B.rename().groupby(psdf.A).value_counts().sort_index(),
              pdf.B.rename().groupby(pdf.A).value_counts().sort_index(),
          )
          self.assert_eq(
              psdf.B.groupby(psdf.A.rename()).value_counts().sort_index(),
              pdf.B.groupby(pdf.A.rename()).value_counts().sort_index(),
          )
          self.assert_eq(
              psdf.B.rename().groupby(psdf.A.rename()).value_counts().sort_index(),
              pdf.B.rename().groupby(pdf.A.rename()).value_counts().sort_index(),
          )
  
      def test_size(self):
          pdf = pd.DataFrame({"A": [1, 2, 2, 3, 3, 3], "B": [1, 1, 2, 3, 3, 3]})
          psdf = ps.from_pandas(pdf)
          self.assert_eq(psdf.groupby("A").size().sort_index(), pdf.groupby("A").size().sort_index())
          self.assert_eq(
              psdf.groupby("A")["B"].size().sort_index(), pdf.groupby("A")["B"].size().sort_index()
          )
          self.assert_eq(
              psdf.groupby("A")[["B"]].size().sort_index(),
              pdf.groupby("A")[["B"]].size().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["A", "B"]).size().sort_index(),
              pdf.groupby(["A", "B"]).size().sort_index(),
          )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("X", "A"), ("Y", "B")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              psdf.groupby(("X", "A")).size().sort_index(),
              pdf.groupby(("X", "A")).size().sort_index(),
          )
          self.assert_eq(
              psdf.groupby([("X", "A"), ("Y", "B")]).size().sort_index(),
              pdf.groupby([("X", "A"), ("Y", "B")]).size().sort_index(),
          )
  
      def test_diff(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 2, 3, 4, 5, 6] * 3,
                  "b": [1, 1, 2, 3, 5, 8] * 3,
                  "c": [1, 4, 9, 16, 25, 36] * 3,
              }
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(psdf.groupby("b").diff().sort_index(), pdf.groupby("b").diff().sort_index())
          self.assert_eq(
              psdf.groupby(["a", "b"]).diff().sort_index(),
              pdf.groupby(["a", "b"]).diff().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["b"])["a"].diff().sort_index(),
              pdf.groupby(["b"])["a"].diff().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["b"])[["a", "b"]].diff().sort_index(),
              pdf.groupby(["b"])[["a", "b"]].diff().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5).diff().sort_index(),
              pdf.groupby(pdf.b // 5).diff().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5)["a"].diff().sort_index(),
              pdf.groupby(pdf.b // 5)["a"].diff().sort_index(),
          )
  
          self.assert_eq(psdf.groupby("b").diff().sum(), pdf.groupby("b").diff().sum().astype(int))
          self.assert_eq(psdf.groupby(["b"])["a"].diff().sum(), pdf.groupby(["b"])["a"].diff().sum())
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              psdf.groupby(("x", "b")).diff().sort_index(),
              pdf.groupby(("x", "b")).diff().sort_index(),
          )
          self.assert_eq(
              psdf.groupby([("x", "a"), ("x", "b")]).diff().sort_index(),
              pdf.groupby([("x", "a"), ("x", "b")]).diff().sort_index(),
          )
  
      def test_rank(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 2, 3, 4, 5, 6] * 3,
                  "b": [1, 1, 2, 3, 5, 8] * 3,
                  "c": [1, 4, 9, 16, 25, 36] * 3,
              },
              index=np.random.rand(6 * 3),
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(psdf.groupby("b").rank().sort_index(), pdf.groupby("b").rank().sort_index())
          self.assert_eq(
              psdf.groupby(["a", "b"]).rank().sort_index(),
              pdf.groupby(["a", "b"]).rank().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["b"])["a"].rank().sort_index(),
              pdf.groupby(["b"])["a"].rank().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["b"])[["a", "c"]].rank().sort_index(),
              pdf.groupby(["b"])[["a", "c"]].rank().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5).rank().sort_index(),
              pdf.groupby(pdf.b // 5).rank().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5)["a"].rank().sort_index(),
              pdf.groupby(pdf.b // 5)["a"].rank().sort_index(),
          )
  
          self.assert_eq(psdf.groupby("b").rank().sum(), pdf.groupby("b").rank().sum())
          self.assert_eq(psdf.groupby(["b"])["a"].rank().sum(), pdf.groupby(["b"])["a"].rank().sum())
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              psdf.groupby(("x", "b")).rank().sort_index(),
              pdf.groupby(("x", "b")).rank().sort_index(),
          )
          self.assert_eq(
              psdf.groupby([("x", "a"), ("x", "b")]).rank().sort_index(),
              pdf.groupby([("x", "a"), ("x", "b")]).rank().sort_index(),
          )
  
      def test_cumcount(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 2, 3, 4, 5, 6] * 3,
                  "b": [1, 1, 2, 3, 5, 8] * 3,
                  "c": [1, 4, 9, 16, 25, 36] * 3,
              },
              index=np.random.rand(6 * 3),
          )
          psdf = ps.from_pandas(pdf)
  
          for ascending in [True, False]:
              self.assert_eq(
                  psdf.groupby("b").cumcount(ascending=ascending).sort_index(),
                  pdf.groupby("b").cumcount(ascending=ascending).sort_index(),
              )
              self.assert_eq(
                  psdf.groupby(["a", "b"]).cumcount(ascending=ascending).sort_index(),
                  pdf.groupby(["a", "b"]).cumcount(ascending=ascending).sort_index(),
              )
              self.assert_eq(
                  psdf.groupby(["b"])["a"].cumcount(ascending=ascending).sort_index(),
                  pdf.groupby(["b"])["a"].cumcount(ascending=ascending).sort_index(),
              )
              self.assert_eq(
                  psdf.groupby(["b"])[["a", "c"]].cumcount(ascending=ascending).sort_index(),
                  pdf.groupby(["b"])[["a", "c"]].cumcount(ascending=ascending).sort_index(),
              )
              self.assert_eq(
                  psdf.groupby(psdf.b // 5).cumcount(ascending=ascending).sort_index(),
                  pdf.groupby(pdf.b // 5).cumcount(ascending=ascending).sort_index(),
              )
              self.assert_eq(
                  psdf.groupby(psdf.b // 5)["a"].cumcount(ascending=ascending).sort_index(),
                  pdf.groupby(pdf.b // 5)["a"].cumcount(ascending=ascending).sort_index(),
              )
              self.assert_eq(
                  psdf.groupby("b").cumcount(ascending=ascending).sum(),
                  pdf.groupby("b").cumcount(ascending=ascending).sum(),
              )
              self.assert_eq(
                  psdf.a.rename().groupby(psdf.b).cumcount(ascending=ascending).sort_index(),
                  pdf.a.rename().groupby(pdf.b).cumcount(ascending=ascending).sort_index(),
              )
              self.assert_eq(
                  psdf.a.groupby(psdf.b.rename()).cumcount(ascending=ascending).sort_index(),
                  pdf.a.groupby(pdf.b.rename()).cumcount(ascending=ascending).sort_index(),
              )
              self.assert_eq(
                  psdf.a.rename().groupby(psdf.b.rename()).cumcount(ascending=ascending).sort_index(),
                  pdf.a.rename().groupby(pdf.b.rename()).cumcount(ascending=ascending).sort_index(),
              )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          for ascending in [True, False]:
              self.assert_eq(
                  psdf.groupby(("x", "b")).cumcount(ascending=ascending).sort_index(),
                  pdf.groupby(("x", "b")).cumcount(ascending=ascending).sort_index(),
              )
              self.assert_eq(
                  psdf.groupby([("x", "a"), ("x", "b")]).cumcount(ascending=ascending).sort_index(),
                  pdf.groupby([("x", "a"), ("x", "b")]).cumcount(ascending=ascending).sort_index(),
              )
  
      def test_cummin(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 2, 3, 4, 5, 6] * 3,
                  "b": [1, 1, 2, 3, 5, 8] * 3,
                  "c": [1, 4, 9, 16, 25, 36] * 3,
              },
              index=np.random.rand(6 * 3),
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              psdf.groupby("b").cummin().sort_index(), pdf.groupby("b").cummin().sort_index()
          )
          self.assert_eq(
              psdf.groupby(["a", "b"]).cummin().sort_index(),
              pdf.groupby(["a", "b"]).cummin().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["b"])["a"].cummin().sort_index(),
              pdf.groupby(["b"])["a"].cummin().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["b"])[["a", "c"]].cummin().sort_index(),
              pdf.groupby(["b"])[["a", "c"]].cummin().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5).cummin().sort_index(),
              pdf.groupby(pdf.b // 5).cummin().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5)["a"].cummin().sort_index(),
              pdf.groupby(pdf.b // 5)["a"].cummin().sort_index(),
          )
          self.assert_eq(
              psdf.groupby("b").cummin().sum().sort_index(),
              pdf.groupby("b").cummin().sum().sort_index(),
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b).cummin().sort_index(),
              pdf.a.rename().groupby(pdf.b).cummin().sort_index(),
          )
          self.assert_eq(
              psdf.a.groupby(psdf.b.rename()).cummin().sort_index(),
              pdf.a.groupby(pdf.b.rename()).cummin().sort_index(),
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b.rename()).cummin().sort_index(),
              pdf.a.rename().groupby(pdf.b.rename()).cummin().sort_index(),
          )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              psdf.groupby(("x", "b")).cummin().sort_index(),
              pdf.groupby(("x", "b")).cummin().sort_index(),
          )
          self.assert_eq(
              psdf.groupby([("x", "a"), ("x", "b")]).cummin().sort_index(),
              pdf.groupby([("x", "a"), ("x", "b")]).cummin().sort_index(),
          )
  
          psdf = ps.DataFrame([["a"], ["b"], ["c"]], columns=["A"])
          self.assertRaises(DataError, lambda: psdf.groupby(["A"]).cummin())
          psdf = ps.DataFrame([[1, "a"], [2, "b"], [3, "c"]], columns=["A", "B"])
          self.assertRaises(DataError, lambda: psdf.groupby(["A"])["B"].cummin())
  
      def test_cummax(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 2, 3, 4, 5, 6] * 3,
                  "b": [1, 1, 2, 3, 5, 8] * 3,
                  "c": [1, 4, 9, 16, 25, 36] * 3,
              },
              index=np.random.rand(6 * 3),
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              psdf.groupby("b").cummax().sort_index(), pdf.groupby("b").cummax().sort_index()
          )
          self.assert_eq(
              psdf.groupby(["a", "b"]).cummax().sort_index(),
              pdf.groupby(["a", "b"]).cummax().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["b"])["a"].cummax().sort_index(),
              pdf.groupby(["b"])["a"].cummax().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["b"])[["a", "c"]].cummax().sort_index(),
              pdf.groupby(["b"])[["a", "c"]].cummax().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5).cummax().sort_index(),
              pdf.groupby(pdf.b // 5).cummax().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5)["a"].cummax().sort_index(),
              pdf.groupby(pdf.b // 5)["a"].cummax().sort_index(),
          )
          self.assert_eq(
              psdf.groupby("b").cummax().sum().sort_index(),
              pdf.groupby("b").cummax().sum().sort_index(),
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b).cummax().sort_index(),
              pdf.a.rename().groupby(pdf.b).cummax().sort_index(),
          )
          self.assert_eq(
              psdf.a.groupby(psdf.b.rename()).cummax().sort_index(),
              pdf.a.groupby(pdf.b.rename()).cummax().sort_index(),
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b.rename()).cummax().sort_index(),
              pdf.a.rename().groupby(pdf.b.rename()).cummax().sort_index(),
          )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              psdf.groupby(("x", "b")).cummax().sort_index(),
              pdf.groupby(("x", "b")).cummax().sort_index(),
          )
          self.assert_eq(
              psdf.groupby([("x", "a"), ("x", "b")]).cummax().sort_index(),
              pdf.groupby([("x", "a"), ("x", "b")]).cummax().sort_index(),
          )
  
          psdf = ps.DataFrame([["a"], ["b"], ["c"]], columns=["A"])
          self.assertRaises(DataError, lambda: psdf.groupby(["A"]).cummax())
          psdf = ps.DataFrame([[1, "a"], [2, "b"], [3, "c"]], columns=["A", "B"])
          self.assertRaises(DataError, lambda: psdf.groupby(["A"])["B"].cummax())
  
      def test_cumsum(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 2, 3, 4, 5, 6] * 3,
                  "b": [1, 1, 2, 3, 5, 8] * 3,
                  "c": [1, 4, 9, 16, 25, 36] * 3,
              },
              index=np.random.rand(6 * 3),
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              psdf.groupby("b").cumsum().sort_index(), pdf.groupby("b").cumsum().sort_index()
          )
          self.assert_eq(
              psdf.groupby(["a", "b"]).cumsum().sort_index(),
              pdf.groupby(["a", "b"]).cumsum().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["b"])["a"].cumsum().sort_index(),
              pdf.groupby(["b"])["a"].cumsum().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["b"])[["a", "c"]].cumsum().sort_index(),
              pdf.groupby(["b"])[["a", "c"]].cumsum().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5).cumsum().sort_index(),
              pdf.groupby(pdf.b // 5).cumsum().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5)["a"].cumsum().sort_index(),
              pdf.groupby(pdf.b // 5)["a"].cumsum().sort_index(),
          )
          self.assert_eq(
              psdf.groupby("b").cumsum().sum().sort_index(),
              pdf.groupby("b").cumsum().sum().sort_index(),
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b).cumsum().sort_index(),
              pdf.a.rename().groupby(pdf.b).cumsum().sort_index(),
          )
          self.assert_eq(
              psdf.a.groupby(psdf.b.rename()).cumsum().sort_index(),
              pdf.a.groupby(pdf.b.rename()).cumsum().sort_index(),
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b.rename()).cumsum().sort_index(),
              pdf.a.rename().groupby(pdf.b.rename()).cumsum().sort_index(),
          )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              psdf.groupby(("x", "b")).cumsum().sort_index(),
              pdf.groupby(("x", "b")).cumsum().sort_index(),
          )
          self.assert_eq(
              psdf.groupby([("x", "a"), ("x", "b")]).cumsum().sort_index(),
              pdf.groupby([("x", "a"), ("x", "b")]).cumsum().sort_index(),
          )
  
          psdf = ps.DataFrame([["a"], ["b"], ["c"]], columns=["A"])
          self.assertRaises(DataError, lambda: psdf.groupby(["A"]).cumsum())
          psdf = ps.DataFrame([[1, "a"], [2, "b"], [3, "c"]], columns=["A", "B"])
          self.assertRaises(DataError, lambda: psdf.groupby(["A"])["B"].cumsum())
  
      def test_cumprod(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 2, -3, 4, -5, 6] * 3,
                  "b": [1, 1, 2, 3, 5, 8] * 3,
                  "c": [1, 0, 9, 16, 25, 36] * 3,
              },
              index=np.random.rand(6 * 3),
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              psdf.groupby("b").cumprod().sort_index(),
              pdf.groupby("b").cumprod().sort_index(),
              check_exact=False,
          )
          self.assert_eq(
              psdf.groupby(["a", "b"]).cumprod().sort_index(),
              pdf.groupby(["a", "b"]).cumprod().sort_index(),
              check_exact=False,
          )
          self.assert_eq(
              psdf.groupby(["b"])["a"].cumprod().sort_index(),
              pdf.groupby(["b"])["a"].cumprod().sort_index(),
              check_exact=False,
          )
          self.assert_eq(
              psdf.groupby(["b"])[["a", "c"]].cumprod().sort_index(),
              pdf.groupby(["b"])[["a", "c"]].cumprod().sort_index(),
              check_exact=False,
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 3).cumprod().sort_index(),
              pdf.groupby(pdf.b // 3).cumprod().sort_index(),
              check_exact=False,
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 3)["a"].cumprod().sort_index(),
              pdf.groupby(pdf.b // 3)["a"].cumprod().sort_index(),
              check_exact=False,
          )
          self.assert_eq(
              psdf.groupby("b").cumprod().sum().sort_index(),
              pdf.groupby("b").cumprod().sum().sort_index(),
              check_exact=False,
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b).cumprod().sort_index(),
              pdf.a.rename().groupby(pdf.b).cumprod().sort_index(),
              check_exact=False,
          )
          self.assert_eq(
              psdf.a.groupby(psdf.b.rename()).cumprod().sort_index(),
              pdf.a.groupby(pdf.b.rename()).cumprod().sort_index(),
              check_exact=False,
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b.rename()).cumprod().sort_index(),
              pdf.a.rename().groupby(pdf.b.rename()).cumprod().sort_index(),
              check_exact=False,
          )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              psdf.groupby(("x", "b")).cumprod().sort_index(),
              pdf.groupby(("x", "b")).cumprod().sort_index(),
              check_exact=False,
          )
          self.assert_eq(
              psdf.groupby([("x", "a"), ("x", "b")]).cumprod().sort_index(),
              pdf.groupby([("x", "a"), ("x", "b")]).cumprod().sort_index(),
              check_exact=False,
          )
  
          psdf = ps.DataFrame([["a"], ["b"], ["c"]], columns=["A"])
          self.assertRaises(DataError, lambda: psdf.groupby(["A"]).cumprod())
          psdf = ps.DataFrame([[1, "a"], [2, "b"], [3, "c"]], columns=["A", "B"])
          self.assertRaises(DataError, lambda: psdf.groupby(["A"])["B"].cumprod())
  
      def test_nsmallest(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 1, 1, 2, 2, 2, 3, 3, 3] * 3,
                  "b": [1, 2, 2, 2, 3, 3, 3, 4, 4] * 3,
                  "c": [1, 2, 2, 2, 3, 3, 3, 4, 4] * 3,
                  "d": [1, 2, 2, 2, 3, 3, 3, 4, 4] * 3,
              },
              index=np.random.rand(9 * 3),
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              psdf.groupby(["a"])["b"].nsmallest(1).sort_values(),
              pdf.groupby(["a"])["b"].nsmallest(1).sort_values(),
          )
          self.assert_eq(
              psdf.groupby(["a"])["b"].nsmallest(2).sort_index(),
              pdf.groupby(["a"])["b"].nsmallest(2).sort_index(),
          )
          self.assert_eq(
              (psdf.b * 10).groupby(psdf.a).nsmallest(2).sort_index(),
              (pdf.b * 10).groupby(pdf.a).nsmallest(2).sort_index(),
          )
          self.assert_eq(
              psdf.b.rename().groupby(psdf.a).nsmallest(2).sort_index(),
              pdf.b.rename().groupby(pdf.a).nsmallest(2).sort_index(),
          )
          self.assert_eq(
              psdf.b.groupby(psdf.a.rename()).nsmallest(2).sort_index(),
              pdf.b.groupby(pdf.a.rename()).nsmallest(2).sort_index(),
          )
          self.assert_eq(
              psdf.b.rename().groupby(psdf.a.rename()).nsmallest(2).sort_index(),
              pdf.b.rename().groupby(pdf.a.rename()).nsmallest(2).sort_index(),
          )
          with self.assertRaisesRegex(ValueError, "nsmallest do not support multi-index now"):
              psdf.set_index(["a", "b"]).groupby(["c"])["d"].nsmallest(1)
  
      def test_nlargest(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 1, 1, 2, 2, 2, 3, 3, 3] * 3,
                  "b": [1, 2, 2, 2, 3, 3, 3, 4, 4] * 3,
                  "c": [1, 2, 2, 2, 3, 3, 3, 4, 4] * 3,
                  "d": [1, 2, 2, 2, 3, 3, 3, 4, 4] * 3,
              },
              index=np.random.rand(9 * 3),
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              psdf.groupby(["a"])["b"].nlargest(1).sort_values(),
              pdf.groupby(["a"])["b"].nlargest(1).sort_values(),
          )
          self.assert_eq(
              psdf.groupby(["a"])["b"].nlargest(2).sort_index(),
              pdf.groupby(["a"])["b"].nlargest(2).sort_index(),
          )
          self.assert_eq(
              (psdf.b * 10).groupby(psdf.a).nlargest(2).sort_index(),
              (pdf.b * 10).groupby(pdf.a).nlargest(2).sort_index(),
          )
          self.assert_eq(
              psdf.b.rename().groupby(psdf.a).nlargest(2).sort_index(),
              pdf.b.rename().groupby(pdf.a).nlargest(2).sort_index(),
          )
          self.assert_eq(
              psdf.b.groupby(psdf.a.rename()).nlargest(2).sort_index(),
              pdf.b.groupby(pdf.a.rename()).nlargest(2).sort_index(),
          )
          self.assert_eq(
              psdf.b.rename().groupby(psdf.a.rename()).nlargest(2).sort_index(),
              pdf.b.rename().groupby(pdf.a.rename()).nlargest(2).sort_index(),
          )
          with self.assertRaisesRegex(ValueError, "nlargest do not support multi-index now"):
              psdf.set_index(["a", "b"]).groupby(["c"])["d"].nlargest(1)
  
      def test_fillna(self):
          pdf = pd.DataFrame(
              {
                  "A": [1, 1, 2, 2] * 3,
                  "B": [2, 4, None, 3] * 3,
                  "C": [None, None, None, 1] * 3,
                  "D": [0, 1, 5, 4] * 3,
              }
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              psdf.groupby("A").fillna(0).sort_index(), pdf.groupby("A").fillna(0).sort_index()
          )
          self.assert_eq(
              psdf.groupby("A")["C"].fillna(0).sort_index(),
              pdf.groupby("A")["C"].fillna(0).sort_index(),
          )
          self.assert_eq(
              psdf.groupby("A")[["C"]].fillna(0).sort_index(),
              pdf.groupby("A")[["C"]].fillna(0).sort_index(),
          )
          self.assert_eq(
              psdf.groupby("A").fillna(method="bfill").sort_index(),
              pdf.groupby("A").fillna(method="bfill").sort_index(),
          )
          self.assert_eq(
              psdf.groupby("A")["C"].fillna(method="bfill").sort_index(),
              pdf.groupby("A")["C"].fillna(method="bfill").sort_index(),
          )
          self.assert_eq(
              psdf.groupby("A")[["C"]].fillna(method="bfill").sort_index(),
              pdf.groupby("A")[["C"]].fillna(method="bfill").sort_index(),
          )
          self.assert_eq(
              psdf.groupby("A").fillna(method="ffill").sort_index(),
              pdf.groupby("A").fillna(method="ffill").sort_index(),
          )
          self.assert_eq(
              psdf.groupby("A")["C"].fillna(method="ffill").sort_index(),
              pdf.groupby("A")["C"].fillna(method="ffill").sort_index(),
          )
          self.assert_eq(
              psdf.groupby("A")[["C"]].fillna(method="ffill").sort_index(),
              pdf.groupby("A")[["C"]].fillna(method="ffill").sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.A // 5).fillna(method="bfill").sort_index(),
              pdf.groupby(pdf.A // 5).fillna(method="bfill").sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.A // 5)["C"].fillna(method="bfill").sort_index(),
              pdf.groupby(pdf.A // 5)["C"].fillna(method="bfill").sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.A // 5)[["C"]].fillna(method="bfill").sort_index(),
              pdf.groupby(pdf.A // 5)[["C"]].fillna(method="bfill").sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.A // 5).fillna(method="ffill").sort_index(),
              pdf.groupby(pdf.A // 5).fillna(method="ffill").sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.A // 5)["C"].fillna(method="ffill").sort_index(),
              pdf.groupby(pdf.A // 5)["C"].fillna(method="ffill").sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.A // 5)[["C"]].fillna(method="ffill").sort_index(),
              pdf.groupby(pdf.A // 5)[["C"]].fillna(method="ffill").sort_index(),
          )
          self.assert_eq(
              psdf.C.rename().groupby(psdf.A).fillna(0).sort_index(),
              pdf.C.rename().groupby(pdf.A).fillna(0).sort_index(),
          )
          self.assert_eq(
              psdf.C.groupby(psdf.A.rename()).fillna(0).sort_index(),
              pdf.C.groupby(pdf.A.rename()).fillna(0).sort_index(),
          )
          self.assert_eq(
              psdf.C.rename().groupby(psdf.A.rename()).fillna(0).sort_index(),
              pdf.C.rename().groupby(pdf.A.rename()).fillna(0).sort_index(),
          )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("X", "A"), ("X", "B"), ("Y", "C"), ("Z", "D")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              psdf.groupby(("X", "A")).fillna(0).sort_index(),
              pdf.groupby(("X", "A")).fillna(0).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(("X", "A")).fillna(method="bfill").sort_index(),
              pdf.groupby(("X", "A")).fillna(method="bfill").sort_index(),
          )
          self.assert_eq(
              psdf.groupby(("X", "A")).fillna(method="ffill").sort_index(),
              pdf.groupby(("X", "A")).fillna(method="ffill").sort_index(),
          )
  
      def test_ffill(self):
          idx = np.random.rand(4 * 3)
          pdf = pd.DataFrame(
              {
                  "A": [1, 1, 2, 2] * 3,
                  "B": [2, 4, None, 3] * 3,
                  "C": [None, None, None, 1] * 3,
                  "D": [0, 1, 5, 4] * 3,
              },
              index=idx,
          )
          psdf = ps.from_pandas(pdf)
  
          if LooseVersion(pd.__version__) <= LooseVersion("0.24.2"):
              self.assert_eq(
                  psdf.groupby("A").ffill().sort_index(),
                  pdf.groupby("A").ffill().sort_index().drop("A", 1),
              )
              self.assert_eq(
                  psdf.groupby("A")[["B"]].ffill().sort_index(),
                  pdf.groupby("A")[["B"]].ffill().sort_index().drop("A", 1),
              )
          else:
              self.assert_eq(
                  psdf.groupby("A").ffill().sort_index(), pdf.groupby("A").ffill().sort_index()
              )
              self.assert_eq(
                  psdf.groupby("A")[["B"]].ffill().sort_index(),
                  pdf.groupby("A")[["B"]].ffill().sort_index(),
              )
          self.assert_eq(
              psdf.groupby("A")["B"].ffill().sort_index(), pdf.groupby("A")["B"].ffill().sort_index()
          )
          self.assert_eq(
              psdf.groupby("A")["B"].ffill()[idx[6]], pdf.groupby("A")["B"].ffill()[idx[6]]
          )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("X", "A"), ("X", "B"), ("Y", "C"), ("Z", "D")])
          pdf.columns = columns
          psdf.columns = columns
  
          if LooseVersion(pd.__version__) <= LooseVersion("0.24.2"):
              self.assert_eq(
                  psdf.groupby(("X", "A")).ffill().sort_index(),
                  pdf.groupby(("X", "A")).ffill().sort_index().drop(("X", "A"), 1),
              )
          else:
              self.assert_eq(
                  psdf.groupby(("X", "A")).ffill().sort_index(),
                  pdf.groupby(("X", "A")).ffill().sort_index(),
              )
  
      def test_bfill(self):
          idx = np.random.rand(4 * 3)
          pdf = pd.DataFrame(
              {
                  "A": [1, 1, 2, 2] * 3,
                  "B": [2, 4, None, 3] * 3,
                  "C": [None, None, None, 1] * 3,
                  "D": [0, 1, 5, 4] * 3,
              },
              index=idx,
          )
          psdf = ps.from_pandas(pdf)
  
          if LooseVersion(pd.__version__) <= LooseVersion("0.24.2"):
              self.assert_eq(
                  psdf.groupby("A").bfill().sort_index(),
                  pdf.groupby("A").bfill().sort_index().drop("A", 1),
              )
              self.assert_eq(
                  psdf.groupby("A")[["B"]].bfill().sort_index(),
                  pdf.groupby("A")[["B"]].bfill().sort_index().drop("A", 1),
              )
          else:
              self.assert_eq(
                  psdf.groupby("A").bfill().sort_index(), pdf.groupby("A").bfill().sort_index()
              )
              self.assert_eq(
                  psdf.groupby("A")[["B"]].bfill().sort_index(),
                  pdf.groupby("A")[["B"]].bfill().sort_index(),
              )
          self.assert_eq(
              psdf.groupby("A")["B"].bfill().sort_index(),
              pdf.groupby("A")["B"].bfill().sort_index(),
          )
          self.assert_eq(
              psdf.groupby("A")["B"].bfill()[idx[6]], pdf.groupby("A")["B"].bfill()[idx[6]]
          )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("X", "A"), ("X", "B"), ("Y", "C"), ("Z", "D")])
          pdf.columns = columns
          psdf.columns = columns
  
          if LooseVersion(pd.__version__) <= LooseVersion("0.24.2"):
              self.assert_eq(
                  psdf.groupby(("X", "A")).bfill().sort_index(),
                  pdf.groupby(("X", "A")).bfill().sort_index().drop(("X", "A"), 1),
              )
          else:
              self.assert_eq(
                  psdf.groupby(("X", "A")).bfill().sort_index(),
                  pdf.groupby(("X", "A")).bfill().sort_index(),
              )
  
      @unittest.skipIf(pd.__version__ < "0.24.0", "not supported before pandas 0.24.0")
      def test_shift(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 1, 2, 2, 3, 3] * 3,
                  "b": [1, 1, 2, 2, 3, 4] * 3,
                  "c": [1, 4, 9, 16, 25, 36] * 3,
              },
              index=np.random.rand(6 * 3),
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              psdf.groupby("a").shift().sort_index(), pdf.groupby("a").shift().sort_index()
          )
          # TODO: seems like a pandas' bug when fill_value is not None?
          # self.assert_eq(psdf.groupby(['a', 'b']).shift(periods=-1, fill_value=0).sort_index(),
          #                pdf.groupby(['a', 'b']).shift(periods=-1, fill_value=0).sort_index())
          self.assert_eq(
              psdf.groupby(["b"])["a"].shift().sort_index(),
              pdf.groupby(["b"])["a"].shift().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["a", "b"])["c"].shift().sort_index(),
              pdf.groupby(["a", "b"])["c"].shift().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5).shift().sort_index(),
              pdf.groupby(pdf.b // 5).shift().sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5)["a"].shift().sort_index(),
              pdf.groupby(pdf.b // 5)["a"].shift().sort_index(),
          )
          # TODO: known pandas' bug when fill_value is not None pandas>=1.0.0
          # https://github.com/pandas-dev/pandas/issues/31971#issue-565171762
          if LooseVersion(pd.__version__) < LooseVersion("1.0.0"):
              self.assert_eq(
                  psdf.groupby(["b"])[["a", "c"]].shift(periods=-1, fill_value=0).sort_index(),
                  pdf.groupby(["b"])[["a", "c"]].shift(periods=-1, fill_value=0).sort_index(),
              )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b).shift().sort_index(),
              pdf.a.rename().groupby(pdf.b).shift().sort_index(),
          )
          self.assert_eq(
              psdf.a.groupby(psdf.b.rename()).shift().sort_index(),
              pdf.a.groupby(pdf.b.rename()).shift().sort_index(),
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b.rename()).shift().sort_index(),
              pdf.a.rename().groupby(pdf.b.rename()).shift().sort_index(),
          )
  
          self.assert_eq(psdf.groupby("a").shift().sum(), pdf.groupby("a").shift().sum().astype(int))
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b).shift().sum(),
              pdf.a.rename().groupby(pdf.b).shift().sum(),
          )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              psdf.groupby(("x", "a")).shift().sort_index(),
              pdf.groupby(("x", "a")).shift().sort_index(),
          )
          # TODO: seems like a pandas' bug when fill_value is not None?
          # self.assert_eq(psdf.groupby([('x', 'a'), ('x', 'b')]).shift(periods=-1,
          #                                                            fill_value=0).sort_index(),
          #                pdf.groupby([('x', 'a'), ('x', 'b')]).shift(periods=-1,
          #                                                            fill_value=0).sort_index())
  
      def test_apply(self):
          pdf = pd.DataFrame(
              {"a": [1, 2, 3, 4, 5, 6], "b": [1, 1, 2, 3, 5, 8], "c": [1, 4, 9, 16, 25, 36]},
              columns=["a", "b", "c"],
          )
          psdf = ps.from_pandas(pdf)
          self.assert_eq(
              psdf.groupby("b").apply(lambda x: x + x.min()).sort_index(),
              pdf.groupby("b").apply(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.groupby("b").apply(len).sort_index(),
              pdf.groupby("b").apply(len).sort_index(),
          )
          self.assert_eq(
              psdf.groupby("b")["a"]
              .apply(lambda x, y, z: x + x.min() + y * z, 10, z=20)
              .sort_index(),
              pdf.groupby("b")["a"].apply(lambda x, y, z: x + x.min() + y * z, 10, z=20).sort_index(),
          )
          self.assert_eq(
              psdf.groupby("b")[["a"]].apply(lambda x: x + x.min()).sort_index(),
              pdf.groupby("b")[["a"]].apply(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["a", "b"])
              .apply(lambda x, y, z: x + x.min() + y + z, 1, z=2)
              .sort_index(),
              pdf.groupby(["a", "b"]).apply(lambda x, y, z: x + x.min() + y + z, 1, z=2).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["b"])["c"].apply(lambda x: 1).sort_index(),
              pdf.groupby(["b"])["c"].apply(lambda x: 1).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["b"])["c"].apply(len).sort_index(),
              pdf.groupby(["b"])["c"].apply(len).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5).apply(lambda x: x + x.min()).sort_index(),
              pdf.groupby(pdf.b // 5).apply(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5)["a"].apply(lambda x: x + x.min()).sort_index(),
              pdf.groupby(pdf.b // 5)["a"].apply(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5)[["a"]].apply(lambda x: x + x.min()).sort_index(),
              pdf.groupby(pdf.b // 5)[["a"]].apply(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5)[["a"]].apply(len).sort_index(),
              pdf.groupby(pdf.b // 5)[["a"]].apply(len).sort_index(),
              almost=True,
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b).apply(lambda x: x + x.min()).sort_index(),
              pdf.a.rename().groupby(pdf.b).apply(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.a.groupby(psdf.b.rename()).apply(lambda x: x + x.min()).sort_index(),
              pdf.a.groupby(pdf.b.rename()).apply(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b.rename()).apply(lambda x: x + x.min()).sort_index(),
              pdf.a.rename().groupby(pdf.b.rename()).apply(lambda x: x + x.min()).sort_index(),
          )
  
          with self.assertRaisesRegex(TypeError, "int object is not callable"):
              psdf.groupby("b").apply(1)
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              psdf.groupby(("x", "b")).apply(lambda x: 1).sort_index(),
              pdf.groupby(("x", "b")).apply(lambda x: 1).sort_index(),
          )
          self.assert_eq(
              psdf.groupby([("x", "a"), ("x", "b")]).apply(lambda x: x + x.min()).sort_index(),
              pdf.groupby([("x", "a"), ("x", "b")]).apply(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(("x", "b")).apply(len).sort_index(),
              pdf.groupby(("x", "b")).apply(len).sort_index(),
          )
          self.assert_eq(
              psdf.groupby([("x", "a"), ("x", "b")]).apply(len).sort_index(),
              pdf.groupby([("x", "a"), ("x", "b")]).apply(len).sort_index(),
          )
  
      def test_apply_without_shortcut(self):
          with option_context("compute.shortcut_limit", 0):
              self.test_apply()
  
      def test_apply_negative(self):
          def func(_) -> ps.Series[int]:
              return pd.Series([1])
  
          with self.assertRaisesRegex(TypeError, "Series as a return type hint at frame groupby"):
              ps.range(10).groupby("id").apply(func)
  
      def test_apply_with_new_dataframe(self):
          pdf = pd.DataFrame(
              {"timestamp": [0.0, 0.5, 1.0, 0.0, 0.5], "car_id": ["A", "A", "A", "B", "B"]}
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              psdf.groupby("car_id").apply(lambda _: pd.DataFrame({"column": [0.0]})).sort_index(),
              pdf.groupby("car_id").apply(lambda _: pd.DataFrame({"column": [0.0]})).sort_index(),
          )
  
          self.assert_eq(
              psdf.groupby("car_id")
              .apply(lambda df: pd.DataFrame({"mean": [df["timestamp"].mean()]}))
              .sort_index(),
              pdf.groupby("car_id")
              .apply(lambda df: pd.DataFrame({"mean": [df["timestamp"].mean()]}))
              .sort_index(),
          )
  
          # dataframe with 1000+ records
          pdf = pd.DataFrame(
              {
                  "timestamp": [0.0, 0.5, 1.0, 0.0, 0.5] * 300,
                  "car_id": ["A", "A", "A", "B", "B"] * 300,
              }
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              psdf.groupby("car_id").apply(lambda _: pd.DataFrame({"column": [0.0]})).sort_index(),
              pdf.groupby("car_id").apply(lambda _: pd.DataFrame({"column": [0.0]})).sort_index(),
          )
  
          self.assert_eq(
              psdf.groupby("car_id")
              .apply(lambda df: pd.DataFrame({"mean": [df["timestamp"].mean()]}))
              .sort_index(),
              pdf.groupby("car_id")
              .apply(lambda df: pd.DataFrame({"mean": [df["timestamp"].mean()]}))
              .sort_index(),
          )
  
      def test_apply_with_new_dataframe_without_shortcut(self):
          with option_context("compute.shortcut_limit", 0):
              self.test_apply_with_new_dataframe()
  
      def test_apply_key_handling(self):
          pdf = pd.DataFrame(
              {"d": [1.0, 1.0, 1.0, 2.0, 2.0, 2.0], "v": [1.0, 2.0, 3.0, 4.0, 5.0, 6.0]}
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              psdf.groupby("d").apply(sum).sort_index(), pdf.groupby("d").apply(sum).sort_index()
          )
  
          with ps.option_context("compute.shortcut_limit", 1):
              self.assert_eq(
                  psdf.groupby("d").apply(sum).sort_index(), pdf.groupby("d").apply(sum).sort_index()
              )
  
      def test_apply_with_side_effect(self):
          pdf = pd.DataFrame(
              {"d": [1.0, 1.0, 1.0, 2.0, 2.0, 2.0], "v": [1.0, 2.0, 3.0, 4.0, 5.0, 6.0]}
          )
          psdf = ps.from_pandas(pdf)
  
          acc = ps.utils.default_session().sparkContext.accumulator(0)
  
          def sum_with_acc_frame(x) -> ps.DataFrame[np.float64, np.float64]:
              nonlocal acc
              acc += 1
              return np.sum(x)
  
          actual = psdf.groupby("d").apply(sum_with_acc_frame).sort_index()
          actual.columns = ["d", "v"]
          self.assert_eq(actual, pdf.groupby("d").apply(sum).sort_index().reset_index(drop=True))
          self.assert_eq(acc.value, 2)
  
          def sum_with_acc_series(x) -> np.float64:
              nonlocal acc
              acc += 1
              return np.sum(x)
  
          self.assert_eq(
              psdf.groupby("d")["v"].apply(sum_with_acc_series).sort_index(),
              pdf.groupby("d")["v"].apply(sum).sort_index().reset_index(drop=True),
          )
          self.assert_eq(acc.value, 4)
  
      def test_transform(self):
          pdf = pd.DataFrame(
              {"a": [1, 2, 3, 4, 5, 6], "b": [1, 1, 2, 3, 5, 8], "c": [1, 4, 9, 16, 25, 36]},
              columns=["a", "b", "c"],
          )
          psdf = ps.from_pandas(pdf)
          self.assert_eq(
              psdf.groupby("b").transform(lambda x: x + x.min()).sort_index(),
              pdf.groupby("b").transform(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.groupby("b")["a"].transform(lambda x: x + x.min()).sort_index(),
              pdf.groupby("b")["a"].transform(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.groupby("b")[["a"]].transform(lambda x: x + x.min()).sort_index(),
              pdf.groupby("b")[["a"]].transform(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["a", "b"]).transform(lambda x: x + x.min()).sort_index(),
              pdf.groupby(["a", "b"]).transform(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["b"])["c"].transform(lambda x: x + x.min()).sort_index(),
              pdf.groupby(["b"])["c"].transform(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5).transform(lambda x: x + x.min()).sort_index(),
              pdf.groupby(pdf.b // 5).transform(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5)["a"].transform(lambda x: x + x.min()).sort_index(),
              pdf.groupby(pdf.b // 5)["a"].transform(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf.b // 5)[["a"]].transform(lambda x: x + x.min()).sort_index(),
              pdf.groupby(pdf.b // 5)[["a"]].transform(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b).transform(lambda x: x + x.min()).sort_index(),
              pdf.a.rename().groupby(pdf.b).transform(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.a.groupby(psdf.b.rename()).transform(lambda x: x + x.min()).sort_index(),
              pdf.a.groupby(pdf.b.rename()).transform(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b.rename()).transform(lambda x: x + x.min()).sort_index(),
              pdf.a.rename().groupby(pdf.b.rename()).transform(lambda x: x + x.min()).sort_index(),
          )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              psdf.groupby(("x", "b")).transform(lambda x: x + x.min()).sort_index(),
              pdf.groupby(("x", "b")).transform(lambda x: x + x.min()).sort_index(),
          )
          self.assert_eq(
              psdf.groupby([("x", "a"), ("x", "b")]).transform(lambda x: x + x.min()).sort_index(),
              pdf.groupby([("x", "a"), ("x", "b")]).transform(lambda x: x + x.min()).sort_index(),
          )
  
      def test_transform_without_shortcut(self):
          with option_context("compute.shortcut_limit", 0):
              self.test_transform()
  
      def test_filter(self):
          pdf = pd.DataFrame(
              {"a": [1, 2, 3, 4, 5, 6], "b": [1, 1, 2, 3, 5, 8], "c": [1, 4, 9, 16, 25, 36]},
              columns=["a", "b", "c"],
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              psdf.groupby("b").filter(lambda x: any(x.a == 2)).sort_index(),
              pdf.groupby("b").filter(lambda x: any(x.a == 2)).sort_index(),
          )
          self.assert_eq(
              psdf.groupby("b")["a"].filter(lambda x: any(x == 2)).sort_index(),
              pdf.groupby("b")["a"].filter(lambda x: any(x == 2)).sort_index(),
          )
          self.assert_eq(
              psdf.groupby("b")[["a"]].filter(lambda x: any(x.a == 2)).sort_index(),
              pdf.groupby("b")[["a"]].filter(lambda x: any(x.a == 2)).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(["a", "b"]).filter(lambda x: any(x.a == 2)).sort_index(),
              pdf.groupby(["a", "b"]).filter(lambda x: any(x.a == 2)).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf["b"] // 5).filter(lambda x: any(x.a == 2)).sort_index(),
              pdf.groupby(pdf["b"] // 5).filter(lambda x: any(x.a == 2)).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf["b"] // 5)["a"].filter(lambda x: any(x == 2)).sort_index(),
              pdf.groupby(pdf["b"] // 5)["a"].filter(lambda x: any(x == 2)).sort_index(),
          )
          self.assert_eq(
              psdf.groupby(psdf["b"] // 5)[["a"]].filter(lambda x: any(x.a == 2)).sort_index(),
              pdf.groupby(pdf["b"] // 5)[["a"]].filter(lambda x: any(x.a == 2)).sort_index(),
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b).filter(lambda x: any(x == 2)).sort_index(),
              pdf.a.rename().groupby(pdf.b).filter(lambda x: any(x == 2)).sort_index(),
          )
          self.assert_eq(
              psdf.a.groupby(psdf.b.rename()).filter(lambda x: any(x == 2)).sort_index(),
              pdf.a.groupby(pdf.b.rename()).filter(lambda x: any(x == 2)).sort_index(),
          )
          self.assert_eq(
              psdf.a.rename().groupby(psdf.b.rename()).filter(lambda x: any(x == 2)).sort_index(),
              pdf.a.rename().groupby(pdf.b.rename()).filter(lambda x: any(x == 2)).sort_index(),
          )
  
          with self.assertRaisesRegex(TypeError, "int object is not callable"):
              psdf.groupby("b").filter(1)
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              psdf.groupby(("x", "b")).filter(lambda x: any(x[("x", "a")] == 2)).sort_index(),
              pdf.groupby(("x", "b")).filter(lambda x: any(x[("x", "a")] == 2)).sort_index(),
          )
          self.assert_eq(
              psdf.groupby([("x", "a"), ("x", "b")])
              .filter(lambda x: any(x[("x", "a")] == 2))
              .sort_index(),
              pdf.groupby([("x", "a"), ("x", "b")])
              .filter(lambda x: any(x[("x", "a")] == 2))
              .sort_index(),
          )
  
      def test_idxmax(self):
          pdf = pd.DataFrame(
              {"a": [1, 1, 2, 2, 3] * 3, "b": [1, 2, 3, 4, 5] * 3, "c": [5, 4, 3, 2, 1] * 3}
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              pdf.groupby(["a"]).idxmax().sort_index(), psdf.groupby(["a"]).idxmax().sort_index()
          )
          self.assert_eq(
              pdf.groupby(["a"]).idxmax(skipna=False).sort_index(),
              psdf.groupby(["a"]).idxmax(skipna=False).sort_index(),
          )
          self.assert_eq(
              pdf.groupby(["a"])["b"].idxmax().sort_index(),
              psdf.groupby(["a"])["b"].idxmax().sort_index(),
          )
          self.assert_eq(
              pdf.b.rename().groupby(pdf.a).idxmax().sort_index(),
              psdf.b.rename().groupby(psdf.a).idxmax().sort_index(),
          )
          self.assert_eq(
              pdf.b.groupby(pdf.a.rename()).idxmax().sort_index(),
              psdf.b.groupby(psdf.a.rename()).idxmax().sort_index(),
          )
          self.assert_eq(
              pdf.b.rename().groupby(pdf.a.rename()).idxmax().sort_index(),
              psdf.b.rename().groupby(psdf.a.rename()).idxmax().sort_index(),
          )
  
          with self.assertRaisesRegex(ValueError, "idxmax only support one-level index now"):
              psdf.set_index(["a", "b"]).groupby(["c"]).idxmax()
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              pdf.groupby(("x", "a")).idxmax().sort_index(),
              psdf.groupby(("x", "a")).idxmax().sort_index(),
          )
          self.assert_eq(
              pdf.groupby(("x", "a")).idxmax(skipna=False).sort_index(),
              psdf.groupby(("x", "a")).idxmax(skipna=False).sort_index(),
          )
  
      def test_idxmin(self):
          pdf = pd.DataFrame(
              {"a": [1, 1, 2, 2, 3] * 3, "b": [1, 2, 3, 4, 5] * 3, "c": [5, 4, 3, 2, 1] * 3}
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              pdf.groupby(["a"]).idxmin().sort_index(), psdf.groupby(["a"]).idxmin().sort_index()
          )
          self.assert_eq(
              pdf.groupby(["a"]).idxmin(skipna=False).sort_index(),
              psdf.groupby(["a"]).idxmin(skipna=False).sort_index(),
          )
          self.assert_eq(
              pdf.groupby(["a"])["b"].idxmin().sort_index(),
              psdf.groupby(["a"])["b"].idxmin().sort_index(),
          )
          self.assert_eq(
              pdf.b.rename().groupby(pdf.a).idxmin().sort_index(),
              psdf.b.rename().groupby(psdf.a).idxmin().sort_index(),
          )
          self.assert_eq(
              pdf.b.groupby(pdf.a.rename()).idxmin().sort_index(),
              psdf.b.groupby(psdf.a.rename()).idxmin().sort_index(),
          )
          self.assert_eq(
              pdf.b.rename().groupby(pdf.a.rename()).idxmin().sort_index(),
              psdf.b.rename().groupby(psdf.a.rename()).idxmin().sort_index(),
          )
  
          with self.assertRaisesRegex(ValueError, "idxmin only support one-level index now"):
              psdf.set_index(["a", "b"]).groupby(["c"]).idxmin()
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              pdf.groupby(("x", "a")).idxmin().sort_index(),
              psdf.groupby(("x", "a")).idxmin().sort_index(),
          )
          self.assert_eq(
              pdf.groupby(("x", "a")).idxmin(skipna=False).sort_index(),
              psdf.groupby(("x", "a")).idxmin(skipna=False).sort_index(),
          )
  
      def test_head(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 1, 1, 1, 2, 2, 2, 3, 3, 3] * 3,
                  "b": [2, 3, 1, 4, 6, 9, 8, 10, 7, 5] * 3,
                  "c": [3, 5, 2, 5, 1, 2, 6, 4, 3, 6] * 3,
              },
              index=np.random.rand(10 * 3),
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              pdf.groupby("a").head(2).sort_index(), psdf.groupby("a").head(2).sort_index()
          )
          self.assert_eq(
              pdf.groupby("a").head(-2).sort_index(), psdf.groupby("a").head(-2).sort_index()
          )
          self.assert_eq(
              pdf.groupby("a").head(100000).sort_index(), psdf.groupby("a").head(100000).sort_index()
          )
  
          self.assert_eq(
              pdf.groupby("a")["b"].head(2).sort_index(), psdf.groupby("a")["b"].head(2).sort_index()
          )
          self.assert_eq(
              pdf.groupby("a")["b"].head(-2).sort_index(),
              psdf.groupby("a")["b"].head(-2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby("a")["b"].head(100000).sort_index(),
              psdf.groupby("a")["b"].head(100000).sort_index(),
          )
  
          self.assert_eq(
              pdf.groupby("a")[["b"]].head(2).sort_index(),
              psdf.groupby("a")[["b"]].head(2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby("a")[["b"]].head(-2).sort_index(),
              psdf.groupby("a")[["b"]].head(-2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby("a")[["b"]].head(100000).sort_index(),
              psdf.groupby("a")[["b"]].head(100000).sort_index(),
          )
  
          self.assert_eq(
              pdf.groupby(pdf.a // 2).head(2).sort_index(),
              psdf.groupby(psdf.a // 2).head(2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby(pdf.a // 2)["b"].head(2).sort_index(),
              psdf.groupby(psdf.a // 2)["b"].head(2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby(pdf.a // 2)[["b"]].head(2).sort_index(),
              psdf.groupby(psdf.a // 2)[["b"]].head(2).sort_index(),
          )
  
          self.assert_eq(
              pdf.b.rename().groupby(pdf.a).head(2).sort_index(),
              psdf.b.rename().groupby(psdf.a).head(2).sort_index(),
          )
          self.assert_eq(
              pdf.b.groupby(pdf.a.rename()).head(2).sort_index(),
              psdf.b.groupby(psdf.a.rename()).head(2).sort_index(),
          )
          self.assert_eq(
              pdf.b.rename().groupby(pdf.a.rename()).head(2).sort_index(),
              psdf.b.rename().groupby(psdf.a.rename()).head(2).sort_index(),
          )
  
          # multi-index
          midx = pd.MultiIndex(
              [["x", "y"], ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j"]],
              [[0, 0, 0, 0, 0, 1, 1, 1, 1, 1], [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]],
          )
          pdf = pd.DataFrame(
              {
                  "a": [1, 1, 1, 1, 2, 2, 2, 3, 3, 3],
                  "b": [2, 3, 1, 4, 6, 9, 8, 10, 7, 5],
                  "c": [3, 5, 2, 5, 1, 2, 6, 4, 3, 6],
              },
              columns=["a", "b", "c"],
              index=midx,
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              pdf.groupby("a").head(2).sort_index(), psdf.groupby("a").head(2).sort_index()
          )
          self.assert_eq(
              pdf.groupby("a").head(-2).sort_index(), psdf.groupby("a").head(-2).sort_index()
          )
          self.assert_eq(
              pdf.groupby("a").head(100000).sort_index(), psdf.groupby("a").head(100000).sort_index()
          )
  
          self.assert_eq(
              pdf.groupby("a")["b"].head(2).sort_index(), psdf.groupby("a")["b"].head(2).sort_index()
          )
          self.assert_eq(
              pdf.groupby("a")["b"].head(-2).sort_index(),
              psdf.groupby("a")["b"].head(-2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby("a")["b"].head(100000).sort_index(),
              psdf.groupby("a")["b"].head(100000).sort_index(),
          )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              pdf.groupby(("x", "a")).head(2).sort_index(),
              psdf.groupby(("x", "a")).head(2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby(("x", "a")).head(-2).sort_index(),
              psdf.groupby(("x", "a")).head(-2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby(("x", "a")).head(100000).sort_index(),
              psdf.groupby(("x", "a")).head(100000).sort_index(),
          )
  
      def test_missing(self):
          psdf = ps.DataFrame({"a": [1, 2, 3, 4, 5, 6, 7, 8, 9]})
  
          # DataFrameGroupBy functions
          missing_functions = inspect.getmembers(
              MissingPandasLikeDataFrameGroupBy, inspect.isfunction
          )
          unsupported_functions = [
              name for (name, type_) in missing_functions if type_.__name__ == "unsupported_function"
          ]
          for name in unsupported_functions:
              with self.assertRaisesRegex(
                  PandasNotImplementedError,
                  "method.*GroupBy.*{}.*not implemented( yet\\.|\\. .+)".format(name),
              ):
                  getattr(psdf.groupby("a"), name)()
  
          deprecated_functions = [
              name for (name, type_) in missing_functions if type_.__name__ == "deprecated_function"
          ]
          for name in deprecated_functions:
              with self.assertRaisesRegex(
                  PandasNotImplementedError, "method.*GroupBy.*{}.*is deprecated".format(name)
              ):
                  getattr(psdf.groupby("a"), name)()
  
          # SeriesGroupBy functions
          missing_functions = inspect.getmembers(MissingPandasLikeSeriesGroupBy, inspect.isfunction)
          unsupported_functions = [
              name for (name, type_) in missing_functions if type_.__name__ == "unsupported_function"
          ]
          for name in unsupported_functions:
              with self.assertRaisesRegex(
                  PandasNotImplementedError,
                  "method.*GroupBy.*{}.*not implemented( yet\\.|\\. .+)".format(name),
              ):
                  getattr(psdf.a.groupby(psdf.a), name)()
  
          deprecated_functions = [
              name for (name, type_) in missing_functions if type_.__name__ == "deprecated_function"
          ]
          for name in deprecated_functions:
              with self.assertRaisesRegex(
                  PandasNotImplementedError, "method.*GroupBy.*{}.*is deprecated".format(name)
              ):
                  getattr(psdf.a.groupby(psdf.a), name)()
  
          # DataFrameGroupBy properties
          missing_properties = inspect.getmembers(
              MissingPandasLikeDataFrameGroupBy, lambda o: isinstance(o, property)
          )
          unsupported_properties = [
              name
              for (name, type_) in missing_properties
              if type_.fget.__name__ == "unsupported_property"
          ]
          for name in unsupported_properties:
              with self.assertRaisesRegex(
                  PandasNotImplementedError,
                  "property.*GroupBy.*{}.*not implemented( yet\\.|\\. .+)".format(name),
              ):
                  getattr(psdf.groupby("a"), name)
          deprecated_properties = [
              name
              for (name, type_) in missing_properties
              if type_.fget.__name__ == "deprecated_property"
          ]
          for name in deprecated_properties:
              with self.assertRaisesRegex(
                  PandasNotImplementedError, "property.*GroupBy.*{}.*is deprecated".format(name)
              ):
                  getattr(psdf.groupby("a"), name)
  
          # SeriesGroupBy properties
          missing_properties = inspect.getmembers(
              MissingPandasLikeSeriesGroupBy, lambda o: isinstance(o, property)
          )
          unsupported_properties = [
              name
              for (name, type_) in missing_properties
              if type_.fget.__name__ == "unsupported_property"
          ]
          for name in unsupported_properties:
              with self.assertRaisesRegex(
                  PandasNotImplementedError,
                  "property.*GroupBy.*{}.*not implemented( yet\\.|\\. .+)".format(name),
              ):
                  getattr(psdf.a.groupby(psdf.a), name)
          deprecated_properties = [
              name
              for (name, type_) in missing_properties
              if type_.fget.__name__ == "deprecated_property"
          ]
          for name in deprecated_properties:
              with self.assertRaisesRegex(
                  PandasNotImplementedError, "property.*GroupBy.*{}.*is deprecated".format(name)
              ):
                  getattr(psdf.a.groupby(psdf.a), name)
  
      @staticmethod
      def test_is_multi_agg_with_relabel():
  
          assert is_multi_agg_with_relabel(a="max") is False
          assert is_multi_agg_with_relabel(a_min=("a", "max"), a_max=("a", "min")) is True
  
      def test_get_group(self):
          pdf = pd.DataFrame(
              [
                  ("falcon", "bird", 389.0),
                  ("parrot", "bird", 24.0),
                  ("lion", "mammal", 80.5),
                  ("monkey", "mammal", np.nan),
              ],
              columns=["name", "class", "max_speed"],
              index=[0, 2, 3, 1],
          )
          pdf.columns.name = "Koalas"
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              psdf.groupby("class").get_group("bird"),
              pdf.groupby("class").get_group("bird"),
          )
          self.assert_eq(
              psdf.groupby("class")["name"].get_group("mammal"),
              pdf.groupby("class")["name"].get_group("mammal"),
          )
          self.assert_eq(
              psdf.groupby("class")[["name"]].get_group("mammal"),
              pdf.groupby("class")[["name"]].get_group("mammal"),
          )
          self.assert_eq(
              psdf.groupby(["class", "name"]).get_group(("mammal", "lion")),
              pdf.groupby(["class", "name"]).get_group(("mammal", "lion")),
          )
          self.assert_eq(
              psdf.groupby(["class", "name"])["max_speed"].get_group(("mammal", "lion")),
              pdf.groupby(["class", "name"])["max_speed"].get_group(("mammal", "lion")),
          )
          self.assert_eq(
              psdf.groupby(["class", "name"])[["max_speed"]].get_group(("mammal", "lion")),
              pdf.groupby(["class", "name"])[["max_speed"]].get_group(("mammal", "lion")),
          )
          self.assert_eq(
              (psdf.max_speed + 1).groupby(psdf["class"]).get_group("mammal"),
              (pdf.max_speed + 1).groupby(pdf["class"]).get_group("mammal"),
          )
          self.assert_eq(
              psdf.groupby("max_speed").get_group(80.5),
              pdf.groupby("max_speed").get_group(80.5),
          )
  
          self.assertRaises(KeyError, lambda: psdf.groupby("class").get_group("fish"))
          self.assertRaises(TypeError, lambda: psdf.groupby("class").get_group(["bird", "mammal"]))
          self.assertRaises(KeyError, lambda: psdf.groupby("class")["name"].get_group("fish"))
          self.assertRaises(
              TypeError, lambda: psdf.groupby("class")["name"].get_group(["bird", "mammal"])
          )
          self.assertRaises(
              KeyError, lambda: psdf.groupby(["class", "name"]).get_group(("lion", "mammal"))
          )
          self.assertRaises(ValueError, lambda: psdf.groupby(["class", "name"]).get_group(("lion",)))
          self.assertRaises(
              ValueError, lambda: psdf.groupby(["class", "name"]).get_group(("mammal",))
          )
          self.assertRaises(ValueError, lambda: psdf.groupby(["class", "name"]).get_group("mammal"))
  
          # MultiIndex columns
          pdf.columns = pd.MultiIndex.from_tuples([("A", "name"), ("B", "class"), ("C", "max_speed")])
          pdf.columns.names = ["Hello", "Koalas"]
          psdf = ps.from_pandas(pdf)
          self.assert_eq(
              psdf.groupby(("B", "class")).get_group("bird"),
              pdf.groupby(("B", "class")).get_group("bird"),
          )
          self.assert_eq(
              psdf.groupby(("B", "class"))[[("A", "name")]].get_group("mammal"),
              pdf.groupby(("B", "class"))[[("A", "name")]].get_group("mammal"),
          )
          self.assert_eq(
              psdf.groupby([("B", "class"), ("A", "name")]).get_group(("mammal", "lion")),
              pdf.groupby([("B", "class"), ("A", "name")]).get_group(("mammal", "lion")),
          )
          self.assert_eq(
              psdf.groupby([("B", "class"), ("A", "name")])[[("C", "max_speed")]].get_group(
                  ("mammal", "lion")
              ),
              pdf.groupby([("B", "class"), ("A", "name")])[[("C", "max_speed")]].get_group(
                  ("mammal", "lion")
              ),
          )
          self.assert_eq(
              (psdf[("C", "max_speed")] + 1).groupby(psdf[("B", "class")]).get_group("mammal"),
              (pdf[("C", "max_speed")] + 1).groupby(pdf[("B", "class")]).get_group("mammal"),
          )
          self.assert_eq(
              psdf.groupby(("C", "max_speed")).get_group(80.5),
              pdf.groupby(("C", "max_speed")).get_group(80.5),
          )
  
          self.assertRaises(KeyError, lambda: psdf.groupby(("B", "class")).get_group("fish"))
          self.assertRaises(
              TypeError, lambda: psdf.groupby(("B", "class")).get_group(["bird", "mammal"])
          )
          self.assertRaises(
              KeyError, lambda: psdf.groupby(("B", "class"))[("A", "name")].get_group("fish")
          )
          self.assertRaises(
              KeyError,
              lambda: psdf.groupby([("B", "class"), ("A", "name")]).get_group(("lion", "mammal")),
          )
          self.assertRaises(
              ValueError,
              lambda: psdf.groupby([("B", "class"), ("A", "name")]).get_group(("lion",)),
          )
          self.assertRaises(
              ValueError, lambda: psdf.groupby([("B", "class"), ("A", "name")]).get_group(("mammal",))
          )
          self.assertRaises(
              ValueError, lambda: psdf.groupby([("B", "class"), ("A", "name")]).get_group("mammal")
          )
  
      def test_median(self):
          psdf = ps.DataFrame(
              {
                  "a": [1.0, 1.0, 1.0, 1.0, 2.0, 2.0, 2.0, 3.0, 3.0, 3.0],
                  "b": [2.0, 3.0, 1.0, 4.0, 6.0, 9.0, 8.0, 10.0, 7.0, 5.0],
                  "c": [3.0, 5.0, 2.0, 5.0, 1.0, 2.0, 6.0, 4.0, 3.0, 6.0],
              },
              columns=["a", "b", "c"],
              index=[7, 2, 4, 1, 3, 4, 9, 10, 5, 6],
          )
          # DataFrame
          expected_result = ps.DataFrame(
              {"b": [2.0, 8.0, 7.0], "c": [3.0, 2.0, 4.0]}, index=pd.Index([1.0, 2.0, 3.0], name="a")
          )
          self.assert_eq(expected_result, psdf.groupby("a").median().sort_index())
          # Series
          expected_result = ps.Series(
              [2.0, 8.0, 7.0], name="b", index=pd.Index([1.0, 2.0, 3.0], name="a")
          )
          self.assert_eq(expected_result, psdf.groupby("a")["b"].median().sort_index())
  
          with self.assertRaisesRegex(TypeError, "accuracy must be an integer; however"):
              psdf.groupby("a").median(accuracy="a")
  
      def test_tail(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 1, 1, 1, 2, 2, 2, 3, 3, 3] * 3,
                  "b": [2, 3, 1, 4, 6, 9, 8, 10, 7, 5] * 3,
                  "c": [3, 5, 2, 5, 1, 2, 6, 4, 3, 6] * 3,
              },
              index=np.random.rand(10 * 3),
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              pdf.groupby("a").tail(2).sort_index(), psdf.groupby("a").tail(2).sort_index()
          )
          self.assert_eq(
              pdf.groupby("a").tail(-2).sort_index(), psdf.groupby("a").tail(-2).sort_index()
          )
          self.assert_eq(
              pdf.groupby("a").tail(100000).sort_index(), psdf.groupby("a").tail(100000).sort_index()
          )
  
          self.assert_eq(
              pdf.groupby("a")["b"].tail(2).sort_index(), psdf.groupby("a")["b"].tail(2).sort_index()
          )
          self.assert_eq(
              pdf.groupby("a")["b"].tail(-2).sort_index(),
              psdf.groupby("a")["b"].tail(-2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby("a")["b"].tail(100000).sort_index(),
              psdf.groupby("a")["b"].tail(100000).sort_index(),
          )
  
          self.assert_eq(
              pdf.groupby("a")[["b"]].tail(2).sort_index(),
              psdf.groupby("a")[["b"]].tail(2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby("a")[["b"]].tail(-2).sort_index(),
              psdf.groupby("a")[["b"]].tail(-2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby("a")[["b"]].tail(100000).sort_index(),
              psdf.groupby("a")[["b"]].tail(100000).sort_index(),
          )
  
          self.assert_eq(
              pdf.groupby(pdf.a // 2).tail(2).sort_index(),
              psdf.groupby(psdf.a // 2).tail(2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby(pdf.a // 2)["b"].tail(2).sort_index(),
              psdf.groupby(psdf.a // 2)["b"].tail(2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby(pdf.a // 2)[["b"]].tail(2).sort_index(),
              psdf.groupby(psdf.a // 2)[["b"]].tail(2).sort_index(),
          )
  
          self.assert_eq(
              pdf.b.rename().groupby(pdf.a).tail(2).sort_index(),
              psdf.b.rename().groupby(psdf.a).tail(2).sort_index(),
          )
          self.assert_eq(
              pdf.b.groupby(pdf.a.rename()).tail(2).sort_index(),
              psdf.b.groupby(psdf.a.rename()).tail(2).sort_index(),
          )
          self.assert_eq(
              pdf.b.rename().groupby(pdf.a.rename()).tail(2).sort_index(),
              psdf.b.rename().groupby(psdf.a.rename()).tail(2).sort_index(),
          )
  
          # multi-index
          midx = pd.MultiIndex(
              [["x", "y"], ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j"]],
              [[0, 0, 0, 0, 0, 1, 1, 1, 1, 1], [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]],
          )
          pdf = pd.DataFrame(
              {
                  "a": [1, 1, 1, 1, 2, 2, 2, 3, 3, 3],
                  "b": [2, 3, 1, 4, 6, 9, 8, 10, 7, 5],
                  "c": [3, 5, 2, 5, 1, 2, 6, 4, 3, 6],
              },
              columns=["a", "b", "c"],
              index=midx,
          )
          psdf = ps.from_pandas(pdf)
  
          self.assert_eq(
              pdf.groupby("a").tail(2).sort_index(), psdf.groupby("a").tail(2).sort_index()
          )
          self.assert_eq(
              pdf.groupby("a").tail(-2).sort_index(), psdf.groupby("a").tail(-2).sort_index()
          )
          self.assert_eq(
              pdf.groupby("a").tail(100000).sort_index(), psdf.groupby("a").tail(100000).sort_index()
          )
  
          self.assert_eq(
              pdf.groupby("a")["b"].tail(2).sort_index(), psdf.groupby("a")["b"].tail(2).sort_index()
          )
          self.assert_eq(
              pdf.groupby("a")["b"].tail(-2).sort_index(),
              psdf.groupby("a")["b"].tail(-2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby("a")["b"].tail(100000).sort_index(),
              psdf.groupby("a")["b"].tail(100000).sort_index(),
          )
  
          # multi-index columns
          columns = pd.MultiIndex.from_tuples([("x", "a"), ("x", "b"), ("y", "c")])
          pdf.columns = columns
          psdf.columns = columns
  
          self.assert_eq(
              pdf.groupby(("x", "a")).tail(2).sort_index(),
              psdf.groupby(("x", "a")).tail(2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby(("x", "a")).tail(-2).sort_index(),
              psdf.groupby(("x", "a")).tail(-2).sort_index(),
          )
          self.assert_eq(
              pdf.groupby(("x", "a")).tail(100000).sort_index(),
              psdf.groupby(("x", "a")).tail(100000).sort_index(),
          )
  
      def test_ddof(self):
          pdf = pd.DataFrame(
              {
                  "a": [1, 1, 1, 1, 2, 2, 2, 3, 3, 3] * 3,
                  "b": [2, 3, 1, 4, 6, 9, 8, 10, 7, 5] * 3,
                  "c": [3, 5, 2, 5, 1, 2, 6, 4, 3, 6] * 3,
              },
              index=np.random.rand(10 * 3),
          )
          psdf = ps.from_pandas(pdf)
  
          for ddof in (0, 1):
              # std
              self.assert_eq(
                  pdf.groupby("a").std(ddof=ddof).sort_index(),
                  psdf.groupby("a").std(ddof=ddof).sort_index(),
                  check_exact=False,
              )
              self.assert_eq(
                  pdf.groupby("a")["b"].std(ddof=ddof).sort_index(),
                  psdf.groupby("a")["b"].std(ddof=ddof).sort_index(),
                  check_exact=False,
              )
              # var
              self.assert_eq(
                  pdf.groupby("a").var(ddof=ddof).sort_index(),
                  psdf.groupby("a").var(ddof=ddof).sort_index(),
                  check_exact=False,
              )
              self.assert_eq(
                  pdf.groupby("a")["b"].var(ddof=ddof).sort_index(),
                  psdf.groupby("a")["b"].var(ddof=ddof).sort_index(),
                  check_exact=False,
              )
  
  
  if __name__ == "__main__":
      from pyspark.pandas.tests.test_groupby import *  # noqa: F401
  
      try:
          import xmlrunner  # type: ignore[import]
  
          testRunner = xmlrunner.XMLTestRunner(output="target/test-reports", verbosity=2)
      except ImportError:
          testRunner = None
      unittest.main(testRunner=testRunner, verbosity=2)
  