DOC: add documentation to IndexSlice (#15623)

Author: jdcla

doc/source/api.rst

@@ -1405,6 +1405,7 @@ MultiIndex
  :toctree: generated/
 
  MultiIndex
+ IndexSlice
 
 MultiIndex Components
 ~~~~~~~~~~~~~~~~~~~~~~

pandas/core/indexing.py

@@ -43,6 +43,36 @@ def get_indexers_list():
 
 # the public IndexSlicerMaker
 class _IndexSlice(object):
+ """
+ Create an object to more easily perform multi-index slicing
+
+ Examples
+ --------
+
+ >>> midx = pd.MultiIndex.from_product([['A0','A1'], ['B0','B1','B2','B3']])
+ >>> columns = ['foo', 'bar']
+ >>> dfmi = pd.DataFrame(np.arange(16).reshape((len(midx), len(columns))),
+ index=midx, columns=columns)
+
+ Using the default slice command:
+
+ >>> dfmi.loc[(slice(None), slice('B0', 'B1')), :]
+ foo bar
+ A0 B0 0 1
+ B1 2 3
+ A1 B0 8 9
+ B1 10 11
+
+ Using the IndexSlice class for a more intuitive command:
+
+ >>> idx = pd.IndexSlice
+ >>> dfmi.loc[idx[:, 'B0':'B1'], :]
+ foo bar
+ A0 B0 0 1
+ B1 2 3
+ A1 B0 8 9
+ B1 10 11
+ """
 
  def __getitem__(self, arg):
  return arg