Make sure numeric_only works for Categorical

Author: Arno Veenstra

pandas/core/arrays/categorical.py

@@ -2172,7 +2172,7 @@ def _reverse_indexer(self):
  return result
 
  # reduction ops #
- def _reduce(self, name, axis=0, skipna=True, **kwargs):
+ def _reduce(self, name, axis=0, **kwargs):
  func = getattr(self, name, None)
  if func is None:
  msg = 'Categorical cannot perform the operation {op}'

pandas/core/series.py

@@ -3674,8 +3674,12 @@ def _reduce(self, op, name, axis=0, skipna=True, numeric_only=None,
  if axis is not None:
  self._get_axis_number(axis)
 
- # dispatch to ExtensionArray interface
- if isinstance(delegate, ExtensionArray):
+ if isinstance(delegate, Categorical):
+ # TODO deprecate numeric_only argument for Categorical and use
+ # skipna as well
+ return delegate._reduce(name, numeric_only=numeric_only, **kwds)
+ elif isinstance(delegate, ExtensionArray):
+ # dispatch to ExtensionArray interface
  return delegate._reduce(name, skipna=skipna, **kwds)
  elif is_datetime64_dtype(delegate):
  # use DatetimeIndex implementation to handle skipna correctly

pandas/tests/reductions/test_reductions.py

@@ -960,6 +960,18 @@ def test_min_max(self):
  assert np.isnan(_min)
  assert _max == 1
 
+ cat = Series(Categorical(
+ ["a", "b", "c", "a"], categories=["b", "c", "d"], ordered=True))
+ _min = cat.min(numeric_only=True)
+ _max = cat.max(numeric_only=True)
+ assert _min == "b"
+ assert _max == "c"
+
+ _min = cat.min(numeric_only=False)
+ _max = cat.max(numeric_only=False)
+ assert np.isnan(_min)
+ assert _max == "c"
+
 
 class TestSeriesMode(object):
  # Note: the name TestSeriesMode indicates these tests