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FIX: Gracefully handle numpy arrays as input to check_in_list() #30714

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Merged
oscargus merged 1 commit into from
Nov 2, 2025
Merged

FIX: Gracefully handle numpy arrays as input to check_in_list() #30714

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16 changes: 15 additions & 1 deletion lib/matplotlib/_api/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -116,6 +116,9 @@ def check_in_list(values, /, *, _print_supported_values=True, **kwargs):
----------
values : iterable
Sequence of values to check on.

Note: All values must support == comparisons.
This means in particular the entries must not be numpy arrays.
_print_supported_values : bool, default: True
Whether to print *values* when raising ValueError.
**kwargs : dict
Expand All @@ -133,7 +136,18 @@ def check_in_list(values, /, *, _print_supported_values=True, **kwargs):
if not kwargs:
raise TypeError("No argument to check!")
for key, val in kwargs.items():
if val not in values:
try:
exists = val in values
except ValueError:
# `in` internally uses `val == values[i]`. There are some objects
# that do not support == to arbitrary other objects, in particular
# numpy arrays.
# Since such objects are not allowed in values, we can gracefully
# handle the case that val (typically provided by users) is of such
# type and directly state it's not in the list instead of letting
# the individual `val == values[i]` ValueError surface.
exists = False
if not exists:
msg = f"{val!r} is not a valid value for {key}"
if _print_supported_values:
msg += f"; supported values are {', '.join(map(repr, values))}"
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5 changes: 5 additions & 0 deletions lib/matplotlib/tests/test_api.py
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Expand Up @@ -150,3 +150,8 @@ def f() -> None:
def test_empty_check_in_list() -> None:
with pytest.raises(TypeError, match="No argument to check!"):
_api.check_in_list(["a"])


def test_check_in_list_numpy() -> None:
with pytest.raises(ValueError, match=r"array\(5\) is not a valid value"):
_api.check_in_list(['a', 'b'], value=np.array(5))
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