code: def test_grouped_with_empty_partition(self):
      data = [Row(id=1, x=2), Row(id=1, x=3), Row(id=2, x=4)]
      expected = [Row(id=1, x=5), Row(id=1, x=5), Row(id=2, x=4)]
      num_parts = len(data) + 1
      df = self.spark.createDataFrame(
          self.sc.parallelize(data, numSlices=num_parts)
      )
  
      f = pandas_udf(
          lambda pdf: pdf.assign(x=pdf["x"].sum()),
          "id long, x int",
          PandasUDFType.GROUPED_MAP,
      )
  
      result = df.groupBy("id").apply(f).collect()
      self.assertEqual(result, expected)
  
imports: import datetime
  import unittest
  from collections import OrderedDict
  from decimal import Decimal
  from typing import cast
  from pyspark.sql import Row
  from pyspark.sql.functions import array, explode, col, lit, udf, sum, pandas_udf, PandasUDFType, window
  from pyspark.sql.types import IntegerType, DoubleType, ArrayType, BinaryType, ByteType, LongType, DecimalType, ShortType, FloatType, StringType, BooleanType, StructType, StructField, NullType, MapType, YearMonthIntervalType
  from pyspark.errors import PythonException, PySparkTypeError
  from pyspark.testing.sqlutils import ReusedSQLTestCase, have_pandas, have_pyarrow, pandas_requirement_message, pyarrow_requirement_message
  from pyspark.testing.utils import QuietTest
label_desc: Use image node_id 38 for calling the GroupedApplyInPandasTestsMixin obj's underlying member method code with example usage: obj.test_grouped_with_empty_partition() without return types