Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly
Sign up
Appearance settings

Commit 52f1aec

Browse files
BUG: avoid validation error for ufunc with string[python] array (#62498)
1 parent 4ee17b3 commit 52f1aec

File tree

3 files changed

+40
-0
lines changed

3 files changed

+40
-0
lines changed

‎doc/source/whatsnew/v2.3.3.rst‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -48,6 +48,7 @@ Bug fixes
4848
with a compiled regex and custom flags (:issue:`62240`)
4949
- Fix :meth:`Series.str.match` and :meth:`Series.str.fullmatch` not matching patterns with groups correctly for the Arrow-backed string dtype (:issue:`61072`)
5050
- Fix comparing a :class:`StringDtype` Series with mixed objects raising an error (:issue:`60228`)
51+
- Fix error being raised when using a numpy ufunc with a Python-backed string array (:issue:`40800`)
5152

5253
Improvements and fixes for Copy-on-Write
5354
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

‎pandas/core/arrays/numpy_.py‎

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -5,6 +5,7 @@
55
Any,
66
Literal,
77
Self,
8+
cast,
89
)
910

1011
import numpy as np
@@ -48,6 +49,7 @@
4849
)
4950

5051
from pandas import Index
52+
from pandas.arrays import StringArray
5153

5254

5355
class NumpyExtensionArray(
@@ -234,6 +236,16 @@ def __array_ufunc__(self, ufunc: np.ufunc, method: str, *inputs, **kwargs):
234236
# e.g. test_np_max_nested_tuples
235237
return result
236238
else:
239+
if self.dtype.type is str: # type: ignore[comparison-overlap]
240+
# StringDtype
241+
self = cast("StringArray", self)
242+
try:
243+
# specify dtype to preserve storage/na_value
244+
return type(self)(result, dtype=self.dtype)
245+
except ValueError:
246+
# if validation of input fails (no strings)
247+
# -> fallback to returning raw numpy array
248+
return result
237249
# one return value; re-box array-like results
238250
return type(self)(result)
239251

‎pandas/tests/arrays/string_/test_string.py‎

Lines changed: 27 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -840,3 +840,30 @@ def test_string_array_view_type_error():
840840
arr = pd.array(["a", "b", "c"], dtype="string")
841841
with pytest.raises(TypeError, match="Cannot change data-type for string array."):
842842
arr.view("i8")
843+
844+
845+
@pytest.mark.parametrize("box", [pd.Series, pd.array])
846+
def test_numpy_array_ufunc(dtype, box):
847+
arr = box(["a", "bb", "ccc"], dtype=dtype)
848+
849+
# custom ufunc that works with string (object) input -> returning numeric
850+
str_len_ufunc = np.frompyfunc(lambda x: len(x), 1, 1)
851+
result = str_len_ufunc(arr)
852+
expected_cls = pd.Series if box is pd.Series else np.array
853+
# TODO we should infer int64 dtype here?
854+
expected = expected_cls([1, 2, 3], dtype=object)
855+
tm.assert_equal(result, expected)
856+
857+
# custom ufunc returning strings
858+
str_multiply_ufunc = np.frompyfunc(lambda x: x * 2, 1, 1)
859+
result = str_multiply_ufunc(arr)
860+
expected = box(["aa", "bbbb", "cccccc"], dtype=dtype)
861+
if dtype.storage == "pyarrow":
862+
# TODO ArrowStringArray should also preserve the class / dtype
863+
if box is pd.array:
864+
expected = np.array(["aa", "bbbb", "cccccc"], dtype=object)
865+
else:
866+
# not specifying the dtype because the exact dtype is not yet preserved
867+
expected = pd.Series(["aa", "bbbb", "cccccc"])
868+
869+
tm.assert_equal(result, expected)

0 commit comments

Comments
(0)

AltStyle によって変換されたページ (->オリジナル) /