fixes based on jreback feedback

Author: Dr-Irv

doc/source/whatsnew/v0.20.0.txt

@@ -42,7 +42,9 @@ Other enhancements
 - ``pd.read_excel`` now preserves sheet order when using ``sheetname=None`` (:issue:`9930`)
 
 - New ``UnsortedIndexError`` (subclass of ``KeyError``) thrown when indexing into an
- unsorted index (:issue:'11897`)
+ unsorted MultiIndex (:issue:'11897`)
+ 
+- Change message when indexing via a boolean ``Series`` that has an incompatible index (:issue:`14491`)
 
 
 .. _whatsnew_0200.api_breaking:

pandas/core/common.py

@@ -97,6 +97,10 @@ class UnsupportedFunctionCall(ValueError):
     pass
 
 
+class UnsortedIndexError(KeyError):
+    pass
+
+
 class AbstractMethodError(NotImplementedError):
     """Raise this error instead of NotImplementedError for abstract methods
     while keeping compatibility with Python 2 and Python 3.

pandas/core/indexing.py

@@ -1814,7 +1814,8 @@ def check_bool_indexer(ax, key):
         result = result.reindex(ax)
         mask = isnull(result._values)
         if mask.any():
-            raise IndexingError('Unalignable labels in boolean Series index')
+            raise IndexingError('Unalignable labels in boolean Series index '
+                                '{}'.format(key.index))
         result = result.astype(bool)._values
     elif is_sparse(result):
         result = result.to_dense()

pandas/indexes/multi.py

@@ -25,7 +25,8 @@
 from pandas.core.common import (_values_from_object,
                                 is_bool_indexer,
                                 is_null_slice,
-                                PerformanceWarning)
+                                PerformanceWarning,
+                                UnsortedIndexError)
 
 
 from pandas.core.base import FrozenList
@@ -45,10 +46,6 @@
 import pandas.indexes.base as ibase
 
 
-class UnsortedIndexError(KeyError):
-    pass
-
-
 class MultiIndex(Index):
     """
     A multi-level, or hierarchical, index object for pandas objects

pandas/tests/indexes/test_multi.py

@@ -8,9 +8,8 @@
 
 from pandas import (DataFrame, date_range, period_range, MultiIndex, Index,
                     CategoricalIndex, compat)
-from pandas.core.common import PerformanceWarning
+from pandas.core.common import PerformanceWarning, UnsortedIndexError
 from pandas.indexes.base import InvalidIndexError
-from pandas.indexes.multi import UnsortedIndexError
 from pandas.compat import range, lrange, u, PY3, long, lzip
 
 import numpy as np

pandas/tests/indexing/test_indexing.py

@@ -23,7 +23,7 @@
                              MultiIndex, Timestamp, Timedelta)
 from pandas.formats.printing import pprint_thing
 from pandas import concat
-from pandas.core.common import PerformanceWarning
+from pandas.core.common import PerformanceWarning, UnsortedIndexError
 
 import pandas.util.testing as tm
 from pandas import date_range
@@ -2230,7 +2230,7 @@ def f():
         df = df.sortlevel(level=1, axis=0)
         self.assertEqual(df.index.lexsort_depth, 0)
         with tm.assertRaisesRegexp(
-                KeyError,
+                UnsortedIndexError,
                 'MultiIndex Slicing requires the index to be fully '
                 r'lexsorted tuple len \(2\), lexsort depth \(0\)'):
             df.loc[(slice(None), df.loc[:, ('a', 'bar')] > 5), :]
@@ -2417,7 +2417,7 @@ def test_per_axis_per_level_doc_examples(self):
         def f():
             df.loc['A1', (slice(None), 'foo')]
 
-        self.assertRaises(KeyError, f)
+        self.assertRaises(UnsortedIndexError, f)
         df = df.sortlevel(axis=1)
 
         # slicing
@@ -3480,8 +3480,10 @@ def test_iloc_mask(self):
             ('index', '.loc'): '0b11',
             ('index', '.iloc'): ('iLocation based boolean indexing '
                                  'cannot use an indexable as a mask'),
-            ('locs', ''): 'Unalignable labels in boolean Series index',
-            ('locs', '.loc'): 'Unalignable labels in boolean Series index',
+            ('locs', ''): 'Unalignable labels in boolean Series index '
+                          "Int64Index([3, 2, 1, 0], dtype='int64')",
+            ('locs', '.loc'): 'Unalignable labels in boolean Series index '
+                          "Int64Index([3, 2, 1, 0], dtype='int64')",
             ('locs', '.iloc'): ('iLocation based boolean indexing on an '
                                 'integer type is not available'),
         }