code: """
  Contains data structures designed for manipulating panel (3-dimensional) data
  """
  # pylint: disable=E1103,W0231,W0212,W0621
  from __future__ import division
  from pandas.compat import (map, zip, range, lrange, lmap, u, OrderedDict,
                             OrderedDefaultdict)
  from pandas import compat
  import sys
  import warnings
  import numpy as np
  from pandas.core.common import (PandasError, _try_sort, _default_index,
                                  _infer_dtype_from_scalar, notnull, is_list_like)
  from pandas.core.categorical import Categorical
  from pandas.core.index import (Index, MultiIndex, _ensure_index,
                                 _get_combined_index)
  from pandas.core.indexing import maybe_droplevels
  from pandas.core.internals import (BlockManager,
                                     create_block_manager_from_arrays,
                                     create_block_manager_from_blocks)
  from pandas.core.series import Series
  from pandas.core.frame import DataFrame
  from pandas.core.generic import NDFrame, _shared_docs
  from pandas.tools.util import cartesian_product
  from pandas import compat
  from pandas.util.decorators import (deprecate, Appender, Substitution,
                                      deprecate_kwarg)
  import pandas.core.common as com
  import pandas.core.ops as ops
  import pandas.core.nanops as nanops
  import pandas.computation.expressions as expressions
  from pandas import lib
  
  _shared_doc_kwargs = dict(
      axes='items, major_axis, minor_axis',
      klass="Panel",
      axes_single_arg="{0,1,2,'items','major_axis','minor_axis'}")
  _shared_doc_kwargs['args_transpose'] = ("three positional arguments: each one"
                                          "of\n        %s" %
                                          _shared_doc_kwargs['axes_single_arg'])
  
  
  def _ensure_like_indices(time, panels):
      """
      Makes sure that time and panels are conformable
      """
      n_time = len(time)
      n_panel = len(panels)
      u_panels = np.unique(panels)  # this sorts!
      u_time = np.unique(time)
      if len(u_time) == n_time:
          time = np.tile(u_time, len(u_panels))
      if len(u_panels) == n_panel:
          panels = np.repeat(u_panels, len(u_time))
      return time, panels
  
  
  def panel_index(time, panels, names=['time', 'panel']):
      """
      Returns a multi-index suitable for a panel-like DataFrame
  
      Parameters
      ----------
      time : array-like
          Time index, does not have to repeat
      panels : array-like
          Panel index, does not have to repeat
      names : list, optional
          List containing the names of the indices
  
      Returns
      -------
      multi_index : MultiIndex
          Time index is the first level, the panels are the second level.
  
      Examples
      --------
      >>> years = range(1960,1963)
      >>> panels = ['A', 'B', 'C']
      >>> panel_idx = panel_index(years, panels)
      >>> panel_idx
      MultiIndex([(1960, 'A'), (1961, 'A'), (1962, 'A'), (1960, 'B'),
                  (1961, 'B'), (1962, 'B'), (1960, 'C'), (1961, 'C'),
                  (1962, 'C')], dtype=object)
  
      or
  
      >>> import numpy as np
      >>> years = np.repeat(range(1960,1963), 3)
      >>> panels = np.tile(['A', 'B', 'C'], 3)
      >>> panel_idx = panel_index(years, panels)
      >>> panel_idx
      MultiIndex([(1960, 'A'), (1960, 'B'), (1960, 'C'), (1961, 'A'),
                  (1961, 'B'), (1961, 'C'), (1962, 'A'), (1962, 'B'),
                  (1962, 'C')], dtype=object)
      """
      time, panels = _ensure_like_indices(time, panels)
      time_factor = Categorical.from_array(time)
      panel_factor = Categorical.from_array(panels)
  
      labels = [time_factor.codes, panel_factor.codes]
      levels = [time_factor.categories, panel_factor.categories]
      return MultiIndex(levels, labels, sortorder=None, names=names,
                        verify_integrity=False)
  
  
  class Panel(NDFrame):
  
      """
      Represents wide format panel data, stored as 3-dimensional array
  
      Parameters
      ----------
      data : ndarray (items x major x minor), or dict of DataFrames
      items : Index or array-like
          axis=0
      major_axis : Index or array-like
          axis=1
      minor_axis : Index or array-like
          axis=2
      dtype : dtype, default None
          Data type to force, otherwise infer
      copy : boolean, default False
          Copy data from inputs. Only affects DataFrame / 2d ndarray input
      """
  
      @property
      def _constructor(self):
          return type(self)
  
      _constructor_sliced = DataFrame
  
      def __init__(self, data=None, items=None, major_axis=None, minor_axis=None,
                   copy=False, dtype=None):
          self._init_data(data=data, items=items, major_axis=major_axis,
                          minor_axis=minor_axis, copy=copy, dtype=dtype)
  
      def _init_data(self, data, copy, dtype, **kwargs):
          """
          Generate ND initialization; axes are passed
          as required objects to __init__
          """
          if data is None:
              data = {}
          if dtype is not None:
              dtype = self._validate_dtype(dtype)
  
          passed_axes = [kwargs.pop(a, None) for a in self._AXIS_ORDERS]
  
          if kwargs:
              raise TypeError('_init_data() got an unexpected keyword '
                      'argument "{0}"'.format(list(kwargs.keys())[0]))
  
          axes = None
          if isinstance(data, BlockManager):
              if any(x is not None for x in passed_axes):
                  axes = [x if x is not None else y
                          for x, y in zip(passed_axes, data.axes)]
              mgr = data
          elif isinstance(data, dict):
              mgr = self._init_dict(data, passed_axes, dtype=dtype)
              copy = False
              dtype = None
          elif isinstance(data, (np.ndarray, list)):
              mgr = self._init_matrix(data, passed_axes, dtype=dtype, copy=copy)
              copy = False
              dtype = None
          else:  # pragma: no cover
              raise PandasError('Panel constructor not properly called!')
  
          NDFrame.__init__(self, mgr, axes=axes, copy=copy, dtype=dtype)
  
      def _init_dict(self, data, axes, dtype=None):
          haxis = axes.pop(self._info_axis_number)
  
          # prefilter if haxis passed
          if haxis is not None:
              haxis = _ensure_index(haxis)
              data = OrderedDict((k, v) for k, v
                                 in compat.iteritems(data) if k in haxis)
          else:
              ks = list(data.keys())
              if not isinstance(data, OrderedDict):
                  ks = _try_sort(ks)
              haxis = Index(ks)
  
          for k, v in compat.iteritems(data):
              if isinstance(v, dict):
                  data[k] = self._constructor_sliced(v)
  
          # extract axis for remaining axes & create the slicemap
          raxes = [self._extract_axis(self, data, axis=i)
                   if a is None else a for i, a in enumerate(axes)]
          raxes_sm = self._extract_axes_for_slice(self, raxes)
  
          # shallow copy
          arrays = []
          haxis_shape = [len(a) for a in raxes]
          for h in haxis:
              v = values = data.get(h)
              if v is None:
                  values = np.empty(haxis_shape, dtype=dtype)
                  values.fill(np.nan)
              elif isinstance(v, self._constructor_sliced):
                  d = raxes_sm.copy()
                  d['copy'] = False
                  v = v.reindex(**d)
                  if dtype is not None:
                      v = v.astype(dtype)
                  values = v.values
              arrays.append(values)
  
          return self._init_arrays(arrays, haxis, [haxis] + raxes)
  
      def _init_arrays(self, arrays, arr_names, axes):
          return create_block_manager_from_arrays(arrays, arr_names, axes)
  
      @classmethod
      def from_dict(cls, data, intersect=False, orient='items', dtype=None):
          """
          Construct Panel from dict of DataFrame objects
  
          Parameters
          ----------
          data : dict
              {field : DataFrame}
          intersect : boolean
              Intersect indexes of input DataFrames
          orient : {'items', 'minor'}, default 'items'
              The "orientation" of the data. If the keys of the passed dict
              should be the items of the result panel, pass 'items'
              (default). Otherwise if the columns of the values of the passed
              DataFrame objects should be the items (which in the case of
              mixed-dtype data you should do), instead pass 'minor'
  
  
          Returns
          -------
          Panel
          """
          orient = orient.lower()
          if orient == 'minor':
              new_data = OrderedDefaultdict(dict)
              for col, df in compat.iteritems(data):
                  for item, s in compat.iteritems(df):
                      new_data[item][col] = s
              data = new_data
          elif orient != 'items':  # pragma: no cover
              raise ValueError('Orientation must be one of {items, minor}.')
  
          d = cls._homogenize_dict(cls, data, intersect=intersect, dtype=dtype)
          ks = list(d['data'].keys())
          if not isinstance(d['data'], OrderedDict):
              ks = list(sorted(ks))
          d[cls._info_axis_name] = Index(ks)
          return cls(**d)
  
      def __getitem__(self, key):
          if isinstance(self._info_axis, MultiIndex):
              return self._getitem_multilevel(key)
          if not (is_list_like(key) or isinstance(key, slice)):
              return super(Panel, self).__getitem__(key)
          return self.ix[key]
  
      def _getitem_multilevel(self, key):
          info = self._info_axis
          loc = info.get_loc(key)
          if isinstance(loc, (slice, np.ndarray)):
              new_index = info[loc]
              result_index = maybe_droplevels(new_index, key)
              slices = [loc] + [slice(None) for x in range(
                  self._AXIS_LEN - 1)]
              new_values = self.values[slices]
  
              d = self._construct_axes_dict(self._AXIS_ORDERS[1:])
              d[self._info_axis_name] = result_index
              result = self._constructor(new_values, **d)
              return result
          else:
              return self._get_item_cache(key)
  
      def _init_matrix(self, data, axes, dtype=None, copy=False):
          values = self._prep_ndarray(self, data, copy=copy)
  
          if dtype is not None:
              try:
                  values = values.astype(dtype)
              except Exception:
                  raise ValueError('failed to cast to %s' % dtype)
  
          shape = values.shape
          fixed_axes = []
          for i, ax in enumerate(axes):
              if ax is None:
                  ax = _default_index(shape[i])
              else:
                  ax = _ensure_index(ax)
              fixed_axes.append(ax)
  
          return create_block_manager_from_blocks([values], fixed_axes)
  
      #----------------------------------------------------------------------
      # Comparison methods
  
      def _compare_constructor(self, other, func):
          if not self._indexed_same(other):
              raise Exception('Can only compare identically-labeled '
                              'same type objects')
  
          new_data = {}
          for col in self._info_axis:
              new_data[col] = func(self[col], other[col])
  
          d = self._construct_axes_dict(copy=False)
          return self._constructor(data=new_data, **d)
  
      #----------------------------------------------------------------------
      # Magic methods
  
      def __unicode__(self):
          """
          Return a string representation for a particular Panel
  
          Invoked by unicode(df) in py2 only.
          Yields a Unicode String in both py2/py3.
          """
  
          class_name = str(self.__class__)
  
          shape = self.shape
          dims = u('Dimensions: %s') % ' x '.join(
              ["%d (%s)" % (s, a) for a, s in zip(self._AXIS_ORDERS, shape)])
  
          def axis_pretty(a):
              v = getattr(self, a)
              if len(v) > 0:
                  return u('%s axis: %s to %s') % (a.capitalize(),
                                                   com.pprint_thing(v[0]),
                                                   com.pprint_thing(v[-1]))
              else:
                  return u('%s axis: None') % a.capitalize()
  
          output = '\n'.join(
              [class_name, dims] + [axis_pretty(a) for a in self._AXIS_ORDERS])
          return output
  
      def _get_plane_axes_index(self, axis):
          """
          Get my plane axes indexes: these are already
          (as compared with higher level planes),
          as we are returning a DataFrame axes indexes
          """
          axis_name = self._get_axis_name(axis)
  
          if axis_name == 'major_axis':
              index = 'minor_axis'
              columns = 'items'
          if axis_name == 'minor_axis':
              index = 'major_axis'
              columns = 'items'
          elif axis_name == 'items':
              index = 'major_axis'
              columns = 'minor_axis'
  
          return index, columns
  
      def _get_plane_axes(self, axis):
          """
          Get my plane axes indexes: these are already
          (as compared with higher level planes),
          as we are returning a DataFrame axes
          """
          return [ self._get_axis(axi) for axi in self._get_plane_axes_index(axis) ]
  
      fromDict = from_dict
  
      def to_sparse(self, fill_value=None, kind='block'):
          """
          Convert to SparsePanel
  
          Parameters
          ----------
          fill_value : float, default NaN
          kind : {'block', 'integer'}
  
          Returns
          -------
          y : SparseDataFrame
          """
          from pandas.core.sparse import SparsePanel
          frames = dict(compat.iteritems(self))
          return SparsePanel(frames, items=self.items,
                             major_axis=self.major_axis,
                             minor_axis=self.minor_axis,
                             default_kind=kind,
                             default_fill_value=fill_value)
  
      def to_excel(self, path, na_rep='', engine=None, **kwargs):
          """
          Write each DataFrame in Panel to a separate excel sheet
  
          Parameters
          ----------
          path : string or ExcelWriter object
              File path or existing ExcelWriter
          na_rep : string, default ''
              Missing data representation
          engine : string, default None
              write engine to use - you can also set this via the options
              ``io.excel.xlsx.writer``, ``io.excel.xls.writer``, and
              ``io.excel.xlsm.writer``.
  
          Other Parameters
          ----------------
          float_format : string, default None
              Format string for floating point numbers
          cols : sequence, optional
              Columns to write
          header : boolean or list of string, default True
              Write out column names. If a list of string is given it is
              assumed to be aliases for the column names
          index : boolean, default True
              Write row names (index)
          index_label : string or sequence, default None
              Column label for index column(s) if desired. If None is given, and
              `header` and `index` are True, then the index names are used. A
              sequence should be given if the DataFrame uses MultiIndex.
          startrow : upper left cell row to dump data frame
          startcol : upper left cell column to dump data frame
  
          Notes
          -----
          Keyword arguments (and na_rep) are passed to the ``to_excel`` method
          for each DataFrame written.
          """
          from pandas.io.excel import ExcelWriter
  
          if isinstance(path, compat.string_types):
              writer = ExcelWriter(path, engine=engine)
          else:
              writer = path
          kwargs['na_rep'] = na_rep
  
          for item, df in compat.iteritems(self):
              name = str(item)
              df.to_excel(writer, name, **kwargs)
          writer.save()
  
      def as_matrix(self):
          self._consolidate_inplace()
          return self._data.as_matrix()
  
      #----------------------------------------------------------------------
      # Getting and setting elements
  
      def get_value(self, *args, **kwargs):
          """
          Quickly retrieve single value at (item, major, minor) location
  
          Parameters
          ----------
          item : item label (panel item)
          major : major axis label (panel item row)
          minor : minor axis label (panel item column)
          takeable : interpret the passed labels as indexers, default False
  
          Returns
          -------
          value : scalar value
          """
          nargs = len(args)
          nreq = self._AXIS_LEN
  
          # require an arg for each axis
          if nargs != nreq:
              raise TypeError('There must be an argument for each axis, you gave'
                              ' {0} args, but {1} are required'.format(nargs,
                                                                       nreq))
          takeable = kwargs.pop('takeable', None)
  
          if kwargs:
              raise TypeError('get_value() got an unexpected keyword '
                      'argument "{0}"'.format(list(kwargs.keys())[0]))
  
          if takeable is True:
              lower = self._iget_item_cache(args[0])
          else:
              lower = self._get_item_cache(args[0])
  
          return lower.get_value(*args[1:], takeable=takeable)
  
      def set_value(self, *args, **kwargs):
          """
          Quickly set single value at (item, major, minor) location
  
          Parameters
          ----------
          item : item label (panel item)
          major : major axis label (panel item row)
          minor : minor axis label (panel item column)
          value : scalar
          takeable : interpret the passed labels as indexers, default False
  
          Returns
          -------
          panel : Panel
              If label combo is contained, will be reference to calling Panel,
              otherwise a new object
          """
          # require an arg for each axis and the value
          nargs = len(args)
          nreq = self._AXIS_LEN + 1
  
          if nargs != nreq:
              raise TypeError('There must be an argument for each axis plus the '
                              'value provided, you gave {0} args, but {1} are '
                              'required'.format(nargs, nreq))
          takeable = kwargs.pop('takeable', None)
  
          if kwargs:
              raise TypeError('set_value() got an unexpected keyword '
                      'argument "{0}"'.format(list(kwargs.keys())[0]))
  
          try:
              if takeable is True:
                  lower = self._iget_item_cache(args[0])
              else:
                  lower = self._get_item_cache(args[0])
  
              lower.set_value(*args[1:], takeable=takeable)
              return self
          except KeyError:
              axes = self._expand_axes(args)
              d = self._construct_axes_dict_from(self, axes, copy=False)
              result = self.reindex(**d)
              args = list(args)
              likely_dtype, args[-1] = _infer_dtype_from_scalar(args[-1])
              made_bigger = not np.array_equal(
                  axes[0], self._info_axis)
              # how to make this logic simpler?
              if made_bigger:
                  com._possibly_cast_item(result, args[0], likely_dtype)
  
              return result.set_value(*args)
  
      def _box_item_values(self, key, values):
          if self.ndim == values.ndim:
              result = self._constructor(values)
  
              # a dup selection will yield a full ndim
              if result._get_axis(0).is_unique:
                  result = result[key]
  
              return result
  
          d = self._construct_axes_dict_for_slice(self._AXIS_ORDERS[1:])
          return self._constructor_sliced(values, **d)
  
      def __setitem__(self, key, value):
          shape = tuple(self.shape)
          if isinstance(value, self._constructor_sliced):
              value = value.reindex(
                  **self._construct_axes_dict_for_slice(self._AXIS_ORDERS[1:]))
              mat = value.values
          elif isinstance(value, np.ndarray):
              if value.shape != shape[1:]:
                  raise ValueError(
                      'shape of value must be {0}, shape of given object was '
                      '{1}'.format(shape[1:], tuple(map(int, value.shape))))
              mat = np.asarray(value)
          elif np.isscalar(value):
              dtype, value = _infer_dtype_from_scalar(value)
              mat = np.empty(shape[1:], dtype=dtype)
              mat.fill(value)
          else:
              raise TypeError('Cannot set item of type: %s' % str(type(value)))
  
          mat = mat.reshape(tuple([1]) + shape[1:])
          NDFrame._set_item(self, key, mat)
  
      def _unpickle_panel_compat(self, state):  # pragma: no cover
          "Unpickle the panel"
          _unpickle = com._unpickle_array
          vals, items, major, minor = state
  
          items = _unpickle(items)
          major = _unpickle(major)
          minor = _unpickle(minor)
          values = _unpickle(vals)
          wp = Panel(values, items, major, minor)
          self._data = wp._data
  
      def conform(self, frame, axis='items'):
          """
          Conform input DataFrame to align with chosen axis pair.
  
          Parameters
          ----------
          frame : DataFrame
          axis : {'items', 'major', 'minor'}
  
              Axis the input corresponds to. E.g., if axis='major', then
              the frame's columns would be items, and the index would be
              values of the minor axis
  
          Returns
          -------
          DataFrame
          """
          axes = self._get_plane_axes(axis)
          return frame.reindex(**self._extract_axes_for_slice(self, axes))
  
      def head(self, n=5):
          raise NotImplementedError
  
      def tail(self, n=5):
          raise NotImplementedError
  
      def _needs_reindex_multi(self, axes, method, level):
          """ don't allow a multi reindex on Panel or above ndim """
          return False
  
      def dropna(self, axis=0, how='any', inplace=False):
          """
          Drop 2D from panel, holding passed axis constant
  
          Parameters
          ----------
          axis : int, default 0
              Axis to hold constant. E.g. axis=1 will drop major_axis entries
              having a certain amount of NA data
          how : {'all', 'any'}, default 'any'
              'any': one or more values are NA in the DataFrame along the
              axis. For 'all' they all must be.
          inplace : bool, default False
              If True, do operation inplace and return None.
  
          Returns
          -------
          dropped : Panel
          """
          axis = self._get_axis_number(axis)
  
          values = self.values
          mask = com.notnull(values)
  
          for ax in reversed(sorted(set(range(self._AXIS_LEN)) - set([axis]))):
              mask = mask.sum(ax)
  
          per_slice = np.prod(values.shape[:axis] + values.shape[axis + 1:])
  
          if how == 'all':
              cond = mask > 0
          else:
              cond = mask == per_slice
  
          new_ax = self._get_axis(axis)[cond]
          result = self.reindex_axis(new_ax, axis=axis)
          if inplace:
              self._update_inplace(result)
          else:
              return result
  
      def _combine(self, other, func, axis=0):
          if isinstance(other, Panel):
              return self._combine_panel(other, func)
          elif isinstance(other, DataFrame):
              return self._combine_frame(other, func, axis=axis)
          elif np.isscalar(other):
              return self._combine_const(other, func)
  
      def _combine_const(self, other, func):
          new_values = func(self.values, other)
          d = self._construct_axes_dict()
          return self._constructor(new_values, **d)
  
      def _combine_frame(self, other, func, axis=0):
          index, columns = self._get_plane_axes(axis)
          axis = self._get_axis_number(axis)
  
          other = other.reindex(index=index, columns=columns)
  
          if axis == 0:
              new_values = func(self.values, other.values)
          elif axis == 1:
              new_values = func(self.values.swapaxes(0, 1), other.values.T)
              new_values = new_values.swapaxes(0, 1)
          elif axis == 2:
              new_values = func(self.values.swapaxes(0, 2), other.values)
              new_values = new_values.swapaxes(0, 2)
  
          return self._constructor(new_values, self.items, self.major_axis,
                                   self.minor_axis)
  
      def _combine_panel(self, other, func):
          items = self.items.union(other.items)
          major = self.major_axis.union(other.major_axis)
          minor = self.minor_axis.union(other.minor_axis)
  
          # could check that everything's the same size, but forget it
          this = self.reindex(items=items, major=major, minor=minor)
          other = other.reindex(items=items, major=major, minor=minor)
  
          result_values = func(this.values, other.values)
  
          return self._constructor(result_values, items, major, minor)
  
      def major_xs(self, key, copy=None):
          """
          Return slice of panel along major axis
  
          Parameters
          ----------
          key : object
              Major axis label
          copy : boolean [deprecated]
              Whether to make a copy of the data
  
          Returns
          -------
          y : DataFrame
              index -> minor axis, columns -> items
  
          Notes
          -----
          major_xs is only for getting, not setting values.
  
          MultiIndex Slicers is a generic way to get/set values on any level or levels
          it is a superset of major_xs functionality, see :ref:`MultiIndex Slicers <advanced.mi_slicers>`
  
          """
          if copy is not None:
              warnings.warn("copy keyword is deprecated, "
                            "default is to return a copy or a view if possible")
  
          return self.xs(key, axis=self._AXIS_LEN - 2)
  
      def minor_xs(self, key, copy=None):
          """
          Return slice of panel along minor axis
  
          Parameters
          ----------
          key : object
              Minor axis label
          copy : boolean [deprecated]
              Whether to make a copy of the data
  
          Returns
          -------
          y : DataFrame
              index -> major axis, columns -> items
  
          Notes
          -----
          minor_xs is only for getting, not setting values.
  
          MultiIndex Slicers is a generic way to get/set values on any level or levels
          it is a superset of minor_xs functionality, see :ref:`MultiIndex Slicers <advanced.mi_slicers>`
  
          """
          if copy is not None:
              warnings.warn("copy keyword is deprecated, "
                            "default is to return a copy or a view if possible")
  
          return self.xs(key, axis=self._AXIS_LEN - 1)
  
      def xs(self, key, axis=1, copy=None):
          """
          Return slice of panel along selected axis
  
          Parameters
          ----------
          key : object
              Label
          axis : {'items', 'major', 'minor}, default 1/'major'
          copy : boolean [deprecated]
              Whether to make a copy of the data
  
          Returns
          -------
          y : ndim(self)-1
  
          Notes
          -----
          xs is only for getting, not setting values.
  
          MultiIndex Slicers is a generic way to get/set values on any level or levels
          it is a superset of xs functionality, see :ref:`MultiIndex Slicers <advanced.mi_slicers>`
  
          """
          if copy is not None:
              warnings.warn("copy keyword is deprecated, "
                            "default is to return a copy or a view if possible")
  
          axis = self._get_axis_number(axis)
          if axis == 0:
              return self[key]
  
          self._consolidate_inplace()
          axis_number = self._get_axis_number(axis)
          new_data = self._data.xs(key, axis=axis_number, copy=False)
          result = self._construct_return_type(new_data)
          copy = new_data.is_mixed_type
          result._set_is_copy(self, copy=copy)
          return result
  
      _xs = xs
  
      def _ixs(self, i, axis=0):
          """
          i : int, slice, or sequence of integers
          axis : int
          """
  
          ax = self._get_axis(axis)
          key = ax[i]
  
          # xs cannot handle a non-scalar key, so just reindex here
          # if we have a multi-index and a single tuple, then its a reduction (GH 7516)
          if not (isinstance(ax, MultiIndex) and isinstance(key, tuple)):
              if is_list_like(key):
                  indexer = {self._get_axis_name(axis): key}
                  return self.reindex(**indexer)
  
          # a reduction
          if axis == 0:
              values = self._data.iget(i)
              return self._box_item_values(key, values)
  
          # xs by position
          self._consolidate_inplace()
          new_data = self._data.xs(i, axis=axis, copy=True, takeable=True)
          return self._construct_return_type(new_data)
  
      def groupby(self, function, axis='major'):
          """
          Group data on given axis, returning GroupBy object
  
          Parameters
          ----------
          function : callable
              Mapping function for chosen access
          axis : {'major', 'minor', 'items'}, default 'major'
  
          Returns
          -------
          grouped : PanelGroupBy
          """
          from pandas.core.groupby import PanelGroupBy
          axis = self._get_axis_number(axis)
          return PanelGroupBy(self, function, axis=axis)
  
      def to_frame(self, filter_observations=True):
          """
          Transform wide format into long (stacked) format as DataFrame whose
          columns are the Panel's items and whose index is a MultiIndex formed
          of the Panel's major and minor axes.
  
          Parameters
          ----------
          filter_observations : boolean, default True
              Drop (major, minor) pairs without a complete set of observations
              across all the items
  
          Returns
          -------
          y : DataFrame
          """
          _, N, K = self.shape
  
          if filter_observations:
              # shaped like the return DataFrame
              mask = com.notnull(self.values).all(axis=0)
              # size = mask.sum()
              selector = mask.ravel()
          else:
              # size = N * K
              selector = slice(None, None)
  
          data = {}
          for item in self.items:
              data[item] = self[item].values.ravel()[selector]
  
          def construct_multi_parts(idx, n_repeat, n_shuffle=1):
              axis_idx = idx.to_hierarchical(n_repeat, n_shuffle)
              labels = [x[selector] for x in axis_idx.labels]
              levels = axis_idx.levels
              names = axis_idx.names
              return labels, levels, names
  
          def construct_index_parts(idx, major=True):
              levels = [idx]
              if major:
                  labels = [np.arange(N).repeat(K)[selector]]
                  names = idx.name or 'major'
              else:
                  labels = np.arange(K).reshape(1, K)[np.zeros(N, dtype=int)]
                  labels = [labels.ravel()[selector]]
                  names = idx.name or 'minor'
              names = [names]
              return labels, levels, names
  
          if isinstance(self.major_axis, MultiIndex):
              major_labels, major_levels, major_names = construct_multi_parts(
                  self.major_axis, n_repeat=K)
          else:
              major_labels, major_levels, major_names = construct_index_parts(
                  self.major_axis)
  
          if isinstance(self.minor_axis, MultiIndex):
              minor_labels, minor_levels, minor_names = construct_multi_parts(
                  self.minor_axis, n_repeat=N, n_shuffle=K)
          else:
              minor_labels, minor_levels, minor_names = construct_index_parts(
                  self.minor_axis, major=False)
  
          levels = major_levels + minor_levels
          labels = major_labels + minor_labels
          names = major_names + minor_names
  
          index = MultiIndex(levels=levels, labels=labels,
                             names=names, verify_integrity=False)
  
          return DataFrame(data, index=index, columns=self.items)
  
      to_long = deprecate('to_long', to_frame)
      toLong = deprecate('toLong', to_frame)
  
      def apply(self, func, axis='major', **kwargs):
          """
          Applies function along input axis of the Panel
  
          Parameters
          ----------
          func : function
              Function to apply to each combination of 'other' axes
              e.g. if axis = 'items', then the combination of major_axis/minor_axis
              will be passed a Series
          axis : {'major', 'minor', 'items'}
          Additional keyword arguments will be passed as keywords to the function
  
          Examples
          --------
          >>> p.apply(numpy.sqrt) # returns a Panel
          >>> p.apply(lambda x: x.sum(), axis=0) # equiv to p.sum(0)
          >>> p.apply(lambda x: x.sum(), axis=1) # equiv to p.sum(1)
          >>> p.apply(lambda x: x.sum(), axis=2) # equiv to p.sum(2)
  
          Returns
          -------
          result : Pandas Object
          """
  
          if kwargs and not isinstance(func, np.ufunc):
              f = lambda x: func(x, **kwargs)
          else:
              f = func
  
          # 2d-slabs
          if isinstance(axis, (tuple,list)) and len(axis) == 2:
              return self._apply_2d(f, axis=axis)
  
          axis = self._get_axis_number(axis)
  
          # try ufunc like
          if isinstance(f, np.ufunc):
              try:
                  result = np.apply_along_axis(func, axis, self.values)
                  return self._wrap_result(result, axis=axis)
              except (AttributeError):
                  pass
  
          # 1d
          return self._apply_1d(f, axis=axis)
  
      def _apply_1d(self, func, axis):
  
          axis_name = self._get_axis_name(axis)
          ax = self._get_axis(axis)
          ndim = self.ndim
          values = self.values
  
          # iter thru the axes
          slice_axis = self._get_axis(axis)
          slice_indexer = [0]*(ndim-1)
          indexer = np.zeros(ndim, 'O')
          indlist = list(range(ndim))
          indlist.remove(axis)
          indexer[axis] = slice(None, None)
          indexer.put(indlist, slice_indexer)
          planes = [ self._get_axis(axi) for axi in indlist ]
          shape = np.array(self.shape).take(indlist)
  
          # all the iteration points
          points = cartesian_product(planes)
  
          results = []
          for i in range(np.prod(shape)):
  
              # construct the object
              pts = tuple([ p[i] for p in points ])
              indexer.put(indlist, slice_indexer)
  
              obj = Series(values[tuple(indexer)],index=slice_axis,name=pts)
              result = func(obj)
  
              results.append(result)
  
              # increment the indexer
              slice_indexer[-1] += 1
              n = -1
              while (slice_indexer[n] >= shape[n]) and (n > (1-ndim)):
                  slice_indexer[n-1] += 1
                  slice_indexer[n] = 0
                  n -= 1
  
          # empty object
          if not len(results):
              return self._constructor(**self._construct_axes_dict())
  
          # same ndim as current
          if isinstance(results[0],Series):
              arr = np.vstack([ r.values for r in results ])
              arr = arr.T.reshape(tuple([len(slice_axis)] + list(shape)))
              tranp = np.array([axis]+indlist).argsort()
              arr = arr.transpose(tuple(list(tranp)))
              return self._constructor(arr,**self._construct_axes_dict())
  
          # ndim-1 shape
          results = np.array(results).reshape(shape)
          if results.ndim == 2 and axis_name != self._info_axis_name:
              results = results.T
              planes = planes[::-1]
          return self._construct_return_type(results,planes)
  
      def _apply_2d(self, func, axis):
          """ handle 2-d slices, equiv to iterating over the other axis """
  
          ndim = self.ndim
          axis = [ self._get_axis_number(a) for a in axis ]
  
          # construct slabs, in 2-d this is a DataFrame result
          indexer_axis = list(range(ndim))
          for a in axis:
              indexer_axis.remove(a)
          indexer_axis = indexer_axis[0]
  
          slicer = [ slice(None,None) ] * ndim
          ax = self._get_axis(indexer_axis)
  
          results = []
          for i, e in enumerate(ax):
  
              slicer[indexer_axis] = i
              sliced = self.iloc[tuple(slicer)]
  
              obj = func(sliced)
              results.append((e,obj))
  
          return self._construct_return_type(dict(results))
  
      def _reduce(self, op, name, axis=0, skipna=True, numeric_only=None,
                  filter_type=None, **kwds):
          if numeric_only:
              raise NotImplementedError(
                  'Panel.{0} does not implement numeric_only.'.format(name))
  
          axis_name = self._get_axis_name(axis)
          axis_number = self._get_axis_number(axis_name)
          f = lambda x: op(x, axis=axis_number, skipna=skipna, **kwds)
  
          result = f(self.values)
  
          axes = self._get_plane_axes(axis_name)
          if result.ndim == 2 and axis_name != self._info_axis_name:
              result = result.T
  
          return self._construct_return_type(result, axes)
  
      def _construct_return_type(self, result, axes=None):
          """ return the type for the ndim of the result """
          ndim = getattr(result,'ndim',None)
  
          # need to assume they are the same
          if ndim is None:
              if isinstance(result,dict):
                  ndim = getattr(list(compat.itervalues(result))[0],'ndim',None)
  
                  # a saclar result
                  if ndim is None:
                      ndim = 0
  
                  # have a dict, so top-level is +1 dim
                  else:
                      ndim += 1
  
          # scalar
          if ndim == 0:
              return Series(result)
  
          # same as self
          elif self.ndim == ndim:
              """ return the construction dictionary for these axes """
              if axes is None:
                  return self._constructor(result)
              return self._constructor(result, **self._construct_axes_dict())
  
          # sliced
          elif self.ndim == ndim + 1:
              if axes is None:
                  return self._constructor_sliced(result)
              return self._constructor_sliced(
                  result, **self._extract_axes_for_slice(self, axes))
  
          raise PandasError('invalid _construct_return_type [self->%s] '
                            '[result->%s]' % (self, result))
  
      def _wrap_result(self, result, axis):
          axis = self._get_axis_name(axis)
          axes = self._get_plane_axes(axis)
          if result.ndim == 2 and axis != self._info_axis_name:
              result = result.T
  
          return self._construct_return_type(result, axes)
  
      @Appender(_shared_docs['reindex'] % _shared_doc_kwargs)
      def reindex(self, items=None, major_axis=None, minor_axis=None, **kwargs):
          major_axis = (major_axis if major_axis is not None
                        else kwargs.pop('major', None))
          minor_axis = (minor_axis if minor_axis is not None
                        else kwargs.pop('minor', None))
          return super(Panel, self).reindex(items=items, major_axis=major_axis,
                                            minor_axis=minor_axis, **kwargs)
  
      @Appender(_shared_docs['rename'] % _shared_doc_kwargs)
      def rename(self, items=None, major_axis=None, minor_axis=None, **kwargs):
          major_axis = (major_axis if major_axis is not None
                        else kwargs.pop('major', None))
          minor_axis = (minor_axis if minor_axis is not None
                        else kwargs.pop('minor', None))
          return super(Panel, self).rename(items=items, major_axis=major_axis,
                                           minor_axis=minor_axis, **kwargs)
  
      @Appender(_shared_docs['reindex_axis'] % _shared_doc_kwargs)
      def reindex_axis(self, labels, axis=0, method=None, level=None, copy=True,
                       limit=None, fill_value=np.nan):
          return super(Panel, self).reindex_axis(labels=labels, axis=axis,
                                                 method=method, level=level,
                                                 copy=copy, limit=limit,
                                                 fill_value=fill_value)
  
      @Appender(_shared_docs['transpose'] % _shared_doc_kwargs)
      def transpose(self, *args, **kwargs):
          return super(Panel, self).transpose(*args, **kwargs)
  
      def count(self, axis='major'):
          """
          Return number of observations over requested axis.
  
          Parameters
          ----------
          axis : {'items', 'major', 'minor'} or {0, 1, 2}
  
          Returns
          -------
          count : DataFrame
          """
          i = self._get_axis_number(axis)
  
          values = self.values
          mask = np.isfinite(values)
          result = mask.sum(axis=i,dtype='int64')
  
          return self._wrap_result(result, axis)
  
      @deprecate_kwarg(old_arg_name='lags', new_arg_name='periods')
      def shift(self, periods=1, freq=None, axis='major'):
          """
          Shift major or minor axis by specified number of leads/lags. Drops
          periods right now compared with DataFrame.shift
  
          Parameters
          ----------
          lags : int
          axis : {'major', 'minor'}
  
          Returns
          -------
          shifted : Panel
          """
          if freq:
              return self.tshift(periods, freq, axis=axis)
  
          if axis == 'items':
              raise ValueError('Invalid axis')
  
          return super(Panel, self).slice_shift(periods, axis=axis)
  
      def tshift(self, periods=1, freq=None, axis='major', **kwds):
          return super(Panel, self).tshift(periods, freq, axis, **kwds)
  
      def join(self, other, how='left', lsuffix='', rsuffix=''):
          """
          Join items with other Panel either on major and minor axes column
  
          Parameters
          ----------
          other : Panel or list of Panels
              Index should be similar to one of the columns in this one
          how : {'left', 'right', 'outer', 'inner'}
              How to handle indexes of the two objects. Default: 'left'
              for joining on index, None otherwise
              * left: use calling frame's index
              * right: use input frame's index
              * outer: form union of indexes
              * inner: use intersection of indexes
          lsuffix : string
              Suffix to use from left frame's overlapping columns
          rsuffix : string
              Suffix to use from right frame's overlapping columns
  
          Returns
          -------
          joined : Panel
          """
          from pandas.tools.merge import concat
  
          if isinstance(other, Panel):
              join_major, join_minor = self._get_join_index(other, how)
              this = self.reindex(major=join_major, minor=join_minor)
              other = other.reindex(major=join_major, minor=join_minor)
              merged_data = this._data.merge(other._data, lsuffix, rsuffix)
              return self._constructor(merged_data)
          else:
              if lsuffix or rsuffix:
                  raise ValueError('Suffixes not supported when passing '
                                   'multiple panels')
  
              if how == 'left':
                  how = 'outer'
                  join_axes = [self.major_axis, self.minor_axis]
              elif how == 'right':
                  raise ValueError('Right join not supported with multiple '
                                   'panels')
              else:
                  join_axes = None
  
              return concat([self] + list(other), axis=0, join=how,
                            join_axes=join_axes, verify_integrity=True)
  
      def update(self, other, join='left', overwrite=True, filter_func=None,
                 raise_conflict=False):
          """
          Modify Panel in place using non-NA values from passed
          Panel, or object coercible to Panel. Aligns on items
  
          Parameters
          ----------
          other : Panel, or object coercible to Panel
          join : How to join individual DataFrames
              {'left', 'right', 'outer', 'inner'}, default 'left'
          overwrite : boolean, default True
              If True then overwrite values for common keys in the calling panel
          filter_func : callable(1d-array) -> 1d-array<boolean>, default None
              Can choose to replace values other than NA. Return True for values
              that should be updated
          raise_conflict : bool
              If True, will raise an error if a DataFrame and other both
              contain data in the same place.
          """
  
          if not isinstance(other, self._constructor):
              other = self._constructor(other)
  
          axis_name = self._info_axis_name
          axis_values = self._info_axis
          other = other.reindex(**{axis_name: axis_values})
  
          for frame in axis_values:
              self[frame].update(other[frame], join, overwrite, filter_func,
                                 raise_conflict)
  
      def _get_join_index(self, other, how):
          if how == 'left':
              join_major, join_minor = self.major_axis, self.minor_axis
          elif how == 'right':
              join_major, join_minor = other.major_axis, other.minor_axis
          elif how == 'inner':
              join_major = self.major_axis.intersection(other.major_axis)
              join_minor = self.minor_axis.intersection(other.minor_axis)
          elif how == 'outer':
              join_major = self.major_axis.union(other.major_axis)
              join_minor = self.minor_axis.union(other.minor_axis)
          return join_major, join_minor
  
      # miscellaneous data creation
      @staticmethod
      def _extract_axes(self, data, axes, **kwargs):
          """ return a list of the axis indicies """
          return [self._extract_axis(self, data, axis=i, **kwargs) for i, a
                  in enumerate(axes)]
  
      @staticmethod
      def _extract_axes_for_slice(self, axes):
          """ return the slice dictionary for these axes """
          return dict([(self._AXIS_SLICEMAP[i], a)
                       for i, a in zip(self._AXIS_ORDERS[self._AXIS_LEN -
                                                         len(axes):], axes)])
  
      @staticmethod
      def _prep_ndarray(self, values, copy=True):
          if not isinstance(values, np.ndarray):
              values = np.asarray(values)
              # NumPy strings are a pain, convert to object
              if issubclass(values.dtype.type, compat.string_types):
                  values = np.array(values, dtype=object, copy=True)
          else:
              if copy:
                  values = values.copy()
          if values.ndim != self._AXIS_LEN:
              raise ValueError("The number of dimensions required is {0}, "
                               "but the number of dimensions of the "
                               "ndarray given was {1}".format(self._AXIS_LEN,
                                                              values.ndim))
          return values
  
      @staticmethod
      def _homogenize_dict(self, frames, intersect=True, dtype=None):
          """
          Conform set of _constructor_sliced-like objects to either
          an intersection of indices / columns or a union.
  
          Parameters
          ----------
          frames : dict
          intersect : boolean, default True
  
          Returns
          -------
          dict of aligned results & indicies
          """
  
          result = dict()
          # caller differs dict/ODict, presered type
          if isinstance(frames, OrderedDict):
              result = OrderedDict()
  
          adj_frames = OrderedDict()
          for k, v in compat.iteritems(frames):
              if isinstance(v, dict):
                  adj_frames[k] = self._constructor_sliced(v)
              else:
                  adj_frames[k] = v
  
          axes = self._AXIS_ORDERS[1:]
          axes_dict = dict([(a, ax) for a, ax in zip(axes, self._extract_axes(
              self, adj_frames, axes, intersect=intersect))])
  
          reindex_dict = dict(
              [(self._AXIS_SLICEMAP[a], axes_dict[a]) for a in axes])
          reindex_dict['copy'] = False
          for key, frame in compat.iteritems(adj_frames):
              if frame is not None:
                  result[key] = frame.reindex(**reindex_dict)
              else:
                  result[key] = None
  
          axes_dict['data'] = result
          return axes_dict
  
      @staticmethod
      def _extract_axis(self, data, axis=0, intersect=False):
  
          index = None
          if len(data) == 0:
              index = Index([])
          elif len(data) > 0:
              raw_lengths = []
              indexes = []
  
          have_raw_arrays = False
          have_frames = False
  
          for v in data.values():
              if isinstance(v, self._constructor_sliced):
                  have_frames = True
                  indexes.append(v._get_axis(axis))
              elif v is not None:
                  have_raw_arrays = True
                  raw_lengths.append(v.shape[axis])
  
          if have_frames:
              index = _get_combined_index(indexes, intersect=intersect)
  
          if have_raw_arrays:
              lengths = list(set(raw_lengths))
              if len(lengths) > 1:
                  raise ValueError('ndarrays must match shape on axis %d' % axis)
  
              if have_frames:
                  if lengths[0] != len(index):
                      raise AssertionError('Length of data and index must match')
              else:
                  index = Index(np.arange(lengths[0]))
  
          if index is None:
              index = Index([])
  
          return _ensure_index(index)
  
      @classmethod
      def _add_aggregate_operations(cls, use_numexpr=True):
          """ add the operations to the cls; evaluate the doc strings again """
  
          # doc strings substitors
          _agg_doc = """
  Wrapper method for %%s
  
  Parameters
  ----------
  other : %s or %s""" % (cls._constructor_sliced.__name__, cls.__name__) + """
  axis : {""" + ', '.join(cls._AXIS_ORDERS) + "}" + """
  Axis to broadcast over
  
  Returns
  -------
  """ + cls.__name__ + "\n"
  
          def _panel_arith_method(op, name, str_rep=None, default_axis=None,
                                  fill_zeros=None, **eval_kwargs):
              def na_op(x, y):
                  try:
                      result = expressions.evaluate(op, str_rep, x, y,
                                                    raise_on_error=True,
                                                    **eval_kwargs)
                  except TypeError:
                      result = op(x, y)
  
                  # handles discrepancy between numpy and numexpr on division/mod
                  # by 0 though, given that these are generally (always?)
                  # non-scalars, I'm not sure whether it's worth it at the moment
                  result = com._fill_zeros(result, x, y, name, fill_zeros)
                  return result
  
              @Substitution(name)
              @Appender(_agg_doc)
              def f(self, other, axis=0):
                  return self._combine(other, na_op, axis=axis)
              f.__name__ = name
              return f
  
          # add `div`, `mul`, `pow`, etc..
          ops.add_flex_arithmetic_methods(
              cls, _panel_arith_method, use_numexpr=use_numexpr,
              flex_comp_method=ops._comp_method_PANEL)
  
  Panel._setup_axes(axes=['items', 'major_axis', 'minor_axis'],
                    info_axis=0,
                    stat_axis=1,
                    aliases={'major': 'major_axis',
                             'minor': 'minor_axis'},
                    slicers={'major_axis': 'index',
                             'minor_axis': 'columns'})
  
  ops.add_special_arithmetic_methods(Panel, **ops.panel_special_funcs)
  Panel._add_aggregate_operations()
  Panel._add_numeric_operations()
  
  WidePanel = Panel
  LongPanel = DataFrame
  
apis: pandas.core.groupby.PanelGroupBy pandas.compat.iteritems pandas.core.generic.NDFrame._set_item pandas.compat.map pandas.core.common._default_index pandas.core.internals.create_block_manager_from_arrays numpy.asarray pandas.core.common._possibly_cast_item pandas.compat.zip pandas.core.categorical.Categorical.from_array numpy.apply_along_axis numpy.isscalar pandas.core.common._fill_zeros numpy.isfinite numpy.vstack pandas.util.decorators.deprecate_kwarg pandas.compat.itervalues pandas.core.common.PandasError pandas.compat.OrderedDefaultdict pandas.util.decorators.Appender pandas.core.index.MultiIndex pandas.core.sparse.SparsePanel pandas.core.common.is_list_like pandas.core.generic.NDFrame.__init__ numpy.unique pandas.core.common._infer_dtype_from_scalar pandas.core.index._ensure_index pandas.core.ops.add_special_arithmetic_methods numpy.zeros pandas.core.common._try_sort pandas.core.indexing.maybe_droplevels pandas.util.decorators.deprecate numpy.arange numpy.prod pandas.core.common.notnull pandas.compat.u pandas.core.ops.add_flex_arithmetic_methods numpy.empty pandas.compat.OrderedDict pandas.core.series.Series pandas.util.decorators.Substitution pandas.core.index.Index pandas.core.index._get_combined_index pandas.computation.expressions.evaluate pandas.compat.range pandas.tools.util.cartesian_product numpy.array_equal numpy.array pandas.core.frame.DataFrame pandas.core.internals.create_block_manager_from_blocks pandas.io.excel.ExcelWriter pandas.core.common.pprint_thing