Address review and fix test

pandas/core/arrays/categorical.py

@@ -2167,8 +2167,7 @@ def _reverse_indexer(self):
         r, counts = libalgos.groupsort_indexer(self.codes.astype('int64'),
                                                categories.size)
         counts = counts.cumsum()
-        result = (r[counts[indexer]:counts[indexer + 1]]
-                  for indexer in range(len(counts) - 1))
+        result = (r[start:end] for start, end in zip(counts, counts[1:]))
         result = dict(zip(categories, result))
         return result
 

pandas/core/arrays/integer.py

@@ -561,7 +561,7 @@ def cmp_method(self, other):
             else:
                 mask = self._mask | mask
 
-            result[mask] = True if op_name == 'ne' else False
+            result[mask] = op_name == 'ne'
             return result
 
         name = '__{name}__'.format(name=op.__name__)

pandas/core/generic.py

@@ -8576,7 +8576,7 @@ def _where(self, cond, other=np.nan, inplace=False, axis=None, level=None,
             cond = self._constructor(cond, **self._construct_axes_dict())
 
         # make sure we are boolean
-        fill_value = True if inplace else False
+        fill_value = bool(inplace)
         cond = cond.fillna(fill_value)
 
         msg = "Boolean array expected for the condition, not {dtype}"

pandas/core/groupby/groupby.py

@@ -442,7 +442,7 @@ def get_converter(s):
                            " with multiple grouping keys")
                     raise ValueError(msg)
 
-            converters = (get_converter(s) for s in index_sample)
+            converters = [get_converter(s) for s in index_sample]
             names = (tuple(f(n) for f, n in zip(converters, name))
                      for name in names)
 

pandas/core/strings.py

@@ -1872,7 +1872,7 @@ def _wrap_result(self, result, use_codes=True,
 
         if expand is None:
             # infer from ndim if expand is not specified
-            expand = False if result.ndim == 1 else True
+            expand = result.ndim != 1
 
         elif expand is True and not isinstance(self._orig, Index):
             # required when expand=True is explicitly specified

pandas/tests/arrays/test_integer.py

@@ -339,7 +339,7 @@ def _compare_other(self, data, op_name, other):
         expected = pd.Series(op(data._data, other))
 
         # fill the nan locations
-        expected[data._mask] = True if op_name == '__ne__' else False
+        expected[data._mask] = op_name == '__ne__'
 
         tm.assert_series_equal(result, expected)
 
@@ -351,7 +351,7 @@ def _compare_other(self, data, op_name, other):
         expected = op(expected, other)
 
         # fill the nan locations
-        expected[data._mask] = True if op_name == '__ne__' else False
+        expected[data._mask] = op_name == '__ne__'
 
         tm.assert_series_equal(result, expected)