May 3, 2025 · May 3, 2025 · May 4, 2025
diff --git a/lib/matplotlib/__init__.py b/lib/matplotlib/__init__.py
                and val is rcsetup._auto_backend_sentinel
                and "backend" in self):
            return
        valid_key = _api.check_getitem(
            self.validate, rcParam=key, _suggest_close_matches=True, _error_cls=KeyError
        )
        try:
            cval = self.validate[key](val)
        except KeyError as err:
            raise KeyError(
                f"{key} is not a valid rc parameter (see rcParams.keys() for "
                f"a list of valid parameters)") from err
            cval = valid_key(val)
        except ValueError as ve:
            raise ValueError(f"Key {key}: {ve}") from None
        self._set(key, cval)
diff --git a/lib/matplotlib/_api/__init__.py b/lib/matplotlib/_api/__init__.py

 """

 import difflib
 import functools
 import itertools
 import pathlib
            )


 def check_getitem(mapping, /, **kwargs):
 def check_getitem(
        mapping, /, _suggest_close_matches=False, _error_cls=ValueError, **kwargs
    ):
    """
    *kwargs* must consist of a single *key, value* pair.  If *key* is in
    *mapping*, return ``mapping[value]``; else, raise an appropriate
    ValueError.

    Parameters
    ----------
    _suggest_close_matches :
        If True, suggest only close matches instead of all valid values.
    _error_cls :
        Class of error to raise.

    Examples
    --------
    >>> _api.check_getitem({"foo": "bar"}, arg=arg)
    try:
        return mapping[v]
    except KeyError:
        raise ValueError(
            f"{v!r} is not a valid value for {k}; supported values are "
            f"{', '.join(map(repr, mapping))}") from None
        if _suggest_close_matches:
            if len(best := difflib.get_close_matches(v, mapping.keys(), cutoff=0.5)):
                suggestion = f"Did you mean one of {best}?"
            else:
                suggestion = ""
        else:
            suggestion = f"Supported values are {', '.join(map(repr, mapping))}"
        raise _error_cls(f"{v!r} is not a valid value for {k}. {suggestion}") from None


 def caching_module_getattr(cls):
diff --git a/lib/matplotlib/_api/__init__.pyi b/lib/matplotlib/_api/__init__.pyi
 from collections.abc import Callable, Generator, Iterable, Mapping, Sequence
 from typing import Any, TypeVar, overload
 from typing import Any,Type,TypeVar, overload
 from typing_extensions import Self  # < Py 3.11

 from numpy.typing import NDArray
    values: Sequence[Any], /, *, _print_supported_values: bool = ..., **kwargs: Any
 ) -> None: ...
 def check_shape(shape: tuple[int | None, ...], /, **kwargs: NDArray) -> None: ...
 def check_getitem(mapping: Mapping[Any, Any], /, **kwargs: Any) -> Any: ...
 def check_getitem(
        mapping: Mapping[Any, _T], /, _suggest_close_matches: bool, _error_cls: Type[Exception], **kwargs: Any
 ) -> _T: ...
 def caching_module_getattr(cls: type) -> Callable[[str], Any]: ...
 @overload
 def define_aliases(
diff --git a/lib/matplotlib/cm.py b/lib/matplotlib/cm.py
        self._builtin_cmaps = tuple(cmaps)

    def __getitem__(self, item):
 try:
 returnself._cmaps[item].copy()
 except KeyError:
    raise KeyError(f"{item!r} is not a known colormap name") from None
 cmap = _api.check_getitem(
            self._cmaps, colormap=item, _suggest_close_matches=True, _error_cls=KeyError
 )
 return cmap.copy()

    def __iter__(self):
        return iter(self._cmaps)
diff --git a/lib/matplotlib/tests/test_colors.py b/lib/matplotlib/tests/test_colors.py
        cmap([value for value, _ in value_color_tuples]),
        to_rgba_array([color for _, color in value_color_tuples]),
    )


 def test_close_error_name():
    with pytest.raises(
        KeyError,
        match=(
            "'grays' is not a valid value for colormap. "
            "Did you mean one of ['gray', 'Grays', 'gray_r']?"
        )):
        matplotlib.colormaps["grays"]
diff --git a/lib/matplotlib/tests/test_style.py b/lib/matplotlib/tests/test_style.py
    with style.context({PARAM: other_value}):
        assert mpl.rcParams[PARAM] == other_value
        x = style.context({PARAM: original_value, 'badparam': None})
        with pytest.raises(KeyError):
        with pytest.raises(
            KeyError, match="\'badparam\' is not a valid value for rcParam. "
        ):
            with x:
                pass
        assert mpl.rcParams[PARAM] == other_value
Original file line number	Diff line number	Diff line change
Expand Up		@@ -740,12 +740,11 @@ def __setitem__(self, key, val):
		and val is rcsetup._auto_backend_sentinel
		and "backend" in self):
		return
		valid_key = _api.check_getitem(
		self.validate, rcParam=key, _suggest_close_matches=True, _error_cls=KeyError
		)
		try:
		cval = self.validate[key](val)
		except KeyError as err:
		raise KeyError(
		f"{key} is not a valid rc parameter (see rcParams.keys() for "
		f"a list of valid parameters)") from err
		cval = valid_key(val)
		except ValueError as ve:
		raise ValueError(f"Key {key}: {ve}") from None
		self._set(key, cval)
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -10,6 +10,7 @@

		"""

		import difflib
		import functools
		import itertools
		import pathlib
Expand DownExpand Up		@@ -174,12 +175,21 @@ def check_shape(shape, /, **kwargs):
		)


		def check_getitem(mapping, /, **kwargs):
		def check_getitem(
		mapping, /, _suggest_close_matches=False, _error_cls=ValueError, **kwargs
Copy link Member timhoffmMay 4, 2025 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. Would it make sense the make this depend on the number of elements by default? Suggest if there are more than N keys, otherwise list all. (Choose N somewhere between 5 and 10). Maybe even don't make this configurable (YAGNI). I feel the automatic decision depending on the number of elements may be all we ever need and we don't need to bother with deciding on the option per call site. We could always change later because this is private. story645 and dstansby reacted with thumbs up emoji
		):
		"""
		kwargs must consist of a single key, value pair. If key is in
		mapping, return ``mapping[value]``; else, raise an appropriate
		ValueError.

		Parameters
		----------
		_suggest_close_matches :
		If True, suggest only close matches instead of all valid values.
		_error_cls :
		Class of error to raise.

		Examples
		--------
		>>> _api.check_getitem({"foo": "bar"}, arg=arg)
Expand All		@@ -190,9 +200,14 @@ def check_getitem(mapping, /, **kwargs):
		try:
		return mapping[v]
		except KeyError:
		raise ValueError(
		f"{v!r} is not a valid value for {k}; supported values are "
		f"{', '.join(map(repr, mapping))}") from None
		if _suggest_close_matches:
		if len(best := difflib.get_close_matches(v, mapping.keys(), cutoff=0.5)):
		suggestion = f"Did you mean one of {best}?"
		else:
		suggestion = ""
		else:
		suggestion = f"Supported values are {', '.join(map(repr, mapping))}"
		raise _error_cls(f"{v!r} is not a valid value for {k}. {suggestion}") from None


		def caching_module_getattr(cls):
Expand Down
Original file line number	Diff line number	Diff line change
		@@ -1,5 +1,5 @@
		from collections.abc import Callable, Generator, Iterable, Mapping, Sequence
		from typing import Any, TypeVar, overload
		from typing import Any,Type,TypeVar, overload
		from typing_extensions import Self # < Py 3.11

		from numpy.typing import NDArray
Expand DownExpand Up		@@ -42,7 +42,9 @@ def check_in_list(
		values: Sequence[Any], /, , _print_supported_values: bool = ..., *kwargs: Any
		) -> None: ...
		def check_shape(shape: tuple[int \| None, ...], /, **kwargs: NDArray) -> None: ...
		def check_getitem(mapping: Mapping[Any, Any], /, **kwargs: Any) -> Any: ...
		def check_getitem(
		mapping: Mapping[Any, _T], /, _suggest_close_matches: bool, _error_cls: Type[Exception], **kwargs: Any
		) -> _T: ...
		def caching_module_getattr(cls: type) -> Callable[[str], Any]: ...
		@overload
		def define_aliases(
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -92,10 +92,10 @@ def __init__(self, cmaps):
		self._builtin_cmaps = tuple(cmaps)

		def __getitem__(self, item):
		try:
		returnself._cmaps[item].copy()
		except KeyError:
		raise KeyError(f"{item!r} is not a known colormap name") from None
		cmap = _api.check_getitem(
		self._cmaps, colormap=item, _suggest_close_matches=True, _error_cls=KeyError
		)
		return cmap.copy()

		def __iter__(self):
		return iter(self._cmaps)
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1828,3 +1828,13 @@ def test_LinearSegmentedColormap_from_list_value_color_tuple():
		cmap([value for value, _ in value_color_tuples]),
		to_rgba_array([color for _, color in value_color_tuples]),
		)


		def test_close_error_name():
		with pytest.raises(
		KeyError,
		match=(
		"'grays' is not a valid value for colormap. "
		"Did you mean one of ['gray', 'Grays', 'gray_r']?"
		)):
		matplotlib.colormaps["grays"]
Original file line number	Diff line number	Diff line change
Expand Up		@@ -140,7 +140,9 @@ def test_context_with_badparam():
		with style.context({PARAM: other_value}):
		assert mpl.rcParams[PARAM] == other_value
		x = style.context({PARAM: original_value, 'badparam': None})
		with pytest.raises(KeyError):
		with pytest.raises(
		KeyError, match="\'badparam\' is not a valid value for rcParam. "
		):
		with x:
		pass
		assert mpl.rcParams[PARAM] == other_value
Expand Down