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BUG: Fix Categorical use_inf_as_na bug #33629

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1 change: 1 addition & 0 deletions doc/source/whatsnew/v1.1.0.rst
Original file line number Diff line number Diff line change
Expand Up @@ -480,6 +480,7 @@ Categorical
- :meth:`Categorical.fillna` now accepts :class:`Categorical` ``other`` argument (:issue:`32420`)
- Bug where :meth:`Categorical.replace` would replace with ``NaN`` whenever the new value and replacement value were equal (:issue:`33288`)
- Bug where an ordered :class:`Categorical` containing only ``NaN`` values would raise rather than returning ``NaN`` when taking the minimum or maximum (:issue:`33450`)
- Bug where :meth:`Series.isna` and :meth:`DataFrame.isna` would raise for categorical dtype when ``pandas.options.mode.use_inf_as_na`` was set to ``True`` (:issue:`33594`)

Datetimelike
^^^^^^^^^^^^
Expand Down
62 changes: 31 additions & 31 deletions pandas/core/dtypes/missing.py
Original file line number Diff line number Diff line change
Expand Up @@ -134,13 +134,13 @@ def _isna_new(obj):
elif isinstance(obj, type):
return False
elif isinstance(obj, (ABCSeries, np.ndarray, ABCIndexClass, ABCExtensionArray)):
return _isna_ndarraylike(obj)
return _isna_ndarraylike(obj, old=False)
elif isinstance(obj, ABCDataFrame):
return obj.isna()
elif isinstance(obj, list):
return _isna_ndarraylike(np.asarray(obj, dtype=object))
return _isna_ndarraylike(np.asarray(obj, dtype=object), old=False)
elif hasattr(obj, "__array__"):
return _isna_ndarraylike(np.asarray(obj))
return _isna_ndarraylike(np.asarray(obj), old=False)
else:
return False

Expand All @@ -165,13 +165,13 @@ def _isna_old(obj):
elif isinstance(obj, type):
return False
elif isinstance(obj, (ABCSeries, np.ndarray, ABCIndexClass, ABCExtensionArray)):
return _isna_ndarraylike_old(obj)
return _isna_ndarraylike(obj, old=True)
elif isinstance(obj, ABCDataFrame):
return obj.isna()
elif isinstance(obj, list):
return _isna_ndarraylike_old(np.asarray(obj, dtype=object))
return _isna_ndarraylike(np.asarray(obj, dtype=object), old=True)
elif hasattr(obj, "__array__"):
return _isna_ndarraylike_old(np.asarray(obj))
return _isna_ndarraylike(np.asarray(obj), old=True)
else:
return False

Expand Down Expand Up @@ -207,40 +207,40 @@ def _use_inf_as_na(key):
globals()["_isna"] = _isna_new


def _isna_ndarraylike(obj):
values = getattr(obj, "_values", obj)
dtype = values.dtype

if is_extension_array_dtype(dtype):
result = values.isna()
elif is_string_dtype(dtype):
result = _isna_string_dtype(values, dtype, old=False)

elif needs_i8_conversion(dtype):
# this is the NaT pattern
result = values.view("i8") == iNaT
else:
result = np.isnan(values)

# box
if isinstance(obj, ABCSeries):
result = obj._constructor(result, index=obj.index, name=obj.name, copy=False)

return result
def _isna_ndarraylike(obj, old: bool = False):
"""
Return an array indicating which values of the input array are NaN / NA.

Parameters
----------
obj: array-like
The input array whose elements are to be checked.
old: bool
Whether or not to treat infinite values as NA.

def _isna_ndarraylike_old(obj):
Returns
-------
array-like
Array of boolean values denoting the NA status of each element.
"""
values = getattr(obj, "_values", obj)
dtype = values.dtype

if is_string_dtype(dtype):
result = _isna_string_dtype(values, dtype, old=True)

if is_extension_array_dtype(dtype):
if old:
result = values.isna() | (values == -np.inf) | (values == np.inf)
else:
result = values.isna()
elif is_string_dtype(dtype):
result = _isna_string_dtype(values, dtype, old=old)
elif needs_i8_conversion(dtype):
# this is the NaT pattern
result = values.view("i8") == iNaT
else:
result = ~np.isfinite(values)
if old:
result = ~np.isfinite(values)
else:
result = np.isnan(values)

# box
if isinstance(obj, ABCSeries):
Expand Down
53 changes: 52 additions & 1 deletion pandas/tests/arrays/categorical/test_missing.py
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,8 @@

from pandas.core.dtypes.dtypes import CategoricalDtype

from pandas import Categorical, Index, Series, isna
import pandas as pd
from pandas import Categorical, DataFrame, Index, Series, isna
import pandas._testing as tm


Expand Down Expand Up @@ -97,3 +98,53 @@ def test_fillna_array(self):
expected = Categorical(["A", "B", "C", "B", "A"], dtype=cat.dtype)
tm.assert_categorical_equal(result, expected)
assert isna(cat[-1]) # didnt modify original inplace

@pytest.mark.parametrize(
"values, expected",
[
([1, 2, 3], np.array([False, False, False])),
([1, 2, np.nan], np.array([False, False, True])),
([1, 2, np.inf], np.array([False, False, True])),
([1, 2, pd.NA], np.array([False, False, True])),
],
)
def test_use_inf_as_na(self, values, expected):
# https://github.com/pandas-dev/pandas/issues/33594
with pd.option_context("mode.use_inf_as_na", True):
cat = Categorical(values)
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Should we also test this with putting the Categorical creation outside of the option context?

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@dsaxton dsaxton Apr 20, 2020

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It turns out that actually fails interestingly enough: #33629 (comment) (if you set the option after constructing the object it loses its effect). What's even more strange is the value displays as NaN:

[ins] In [3]: arr = pd.Categorical([1, 2, np.inf])                                                                                                                                                           

[ins] In [4]: pd.options.mode.use_inf_as_na = True                                                                                                                                                           

[ins] In [5]: arr                                                                                                                                                                                            
Out[5]: 
[1.0, 2.0, NaN]
Categories (3, float64): [1.0, 2.0, NaN]

[ins] In [6]: arr.isna()                                                                                                                                                                                     
Out[6]: array([False, False, False])

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What's even more strange is the value displays as NaN:

I think that is somewhat "expected", given the discussion above in #33629 (comment) (not that I like that behaviour though).

But regardless of how the categorical is created (with or without the option), I find it very strange that isna is then failing

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@jorisvandenbossche jorisvandenbossche Apr 20, 2020

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Hmm, being a bit confused in the comment above :)
The Categorical.isna is failing, of course, since it just looks at -1 in the codes, and when inf is part of the categories, it is not -1 in the codes. Hence it is failing to detect it.

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@dsaxton so could you additionally test it for pd.isna ? In constract to Categorical.isna(), pd.isna should work even if the Categorical is created before the context, I think?

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@jorisvandenbossche Added some tests, let me know if this is roughly what you had in mind

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Yes, that looks good!

result = cat.isna()
tm.assert_numpy_array_equal(result, expected)

result = Series(cat).isna()
expected = Series(expected)
tm.assert_series_equal(result, expected)

result = DataFrame(cat).isna()
expected = DataFrame(expected)
tm.assert_frame_equal(result, expected)

@pytest.mark.parametrize(
"values, expected",
[
([1, 2, 3], np.array([False, False, False])),
([1, 2, np.nan], np.array([False, False, True])),
([1, 2, np.inf], np.array([False, False, True])),
([1, 2, pd.NA], np.array([False, False, True])),
],
)
def test_use_inf_as_na_outside_context(self, values, expected):
# https://github.com/pandas-dev/pandas/issues/33594
# Using isna directly for Categorical will fail in general here
cat = Categorical(values)

with pd.option_context("mode.use_inf_as_na", True):
result = pd.isna(cat)
tm.assert_numpy_array_equal(result, expected)

result = pd.isna(Series(cat))
expected = Series(expected)
tm.assert_series_equal(result, expected)

result = pd.isna(DataFrame(cat))
expected = DataFrame(expected)
tm.assert_frame_equal(result, expected)