Mar 31, 2023 · Mar 31, 2023 · Mar 31, 2023 · Mar 31, 2023 · Apr 1, 2023 · Apr 20, 2023
diff --git a/doc/users/next_whats_new/updated_scatter.rst b/doc/users/next_whats_new/updated_scatter.rst
 Enable configuration of empty markers in `~matplotlib.axes.Axes.scatter`
 ------------------------------------------------------------------------

 `~matplotlib.axes.Axes.scatter` can now be configured to plot empty markers by setting ``facecolors`` to *'none'* and defining ``c``. In this case, ``c`` will be now used as ``edgecolor``.

 .. plot::
    :include-source: true
    :alt: A simple scatter plot which illustrates the use of the *scatter* function to plot empty markers.

    import numpy as np
    import matplotlib.pyplot as plt

    x = np.arange(0, 10)
    plt.scatter(x, x, c=x, facecolors='none', marker='o')
    plt.show()
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py

        Argument precedence for facecolors:

        - kwargs['facecolor'] if 'none'
        - kwargs['facecolors'] if 'none'
        - c (if not None)
        - kwargs['facecolor']
        - kwargs['facecolors']
        - kwargs['edgecolor']
        - edgecolors (is an explicit kw argument in scatter())
        - kwargs['color'] (==kwcolor)
        - c (if not None)
        - 'face' if not in classic mode else None

        Parameters
        colors : array(N, 4) or None
            The facecolors as RGBA values, or *None* if a colormap is used.
        edgecolors
            The edgecolor.
            The edgecolor, or *None* if a colormap is used.

        """
        facecolors = kwargs.pop('facecolors', None)
            if facecolors is None:
                facecolors = kwcolor

        if edgecolors is None and not mpl.rcParams['_internal.classic_mode']:
        edge_from_c = edgecolors is None and c is not None

        facecolors_none = cbook._str_lower_equal(facecolors, 'none')
        if (edgecolors is None and not mpl.rcParams['_internal.classic_mode']
                and (not edge_from_c or not facecolors_none)):

            edgecolors = mpl.rcParams['scatter.edgecolors']

        c_was_none = c is None
        if not c_is_mapped:
            try:  # Is 'c' acceptable as PathCollection facecolors?
                colors = mcolors.to_rgba_array(c)
                if edge_from_c and facecolors is not None:
                    edgecolors = mcolors.to_rgba_array(c)
            except (TypeError, ValueError) as err:
                if "RGBA values should be within 0-1 range" in str(err):
                    raise
                    raise invalid_shape_exception(len(colors), xsize)
        else:
            colors = None  # use cmap, norm after collection is created
        if cbook._str_lower_equal(facecolors, 'none'):
            colors = facecolors
        return c, colors, edgecolors

    @_preprocess_data(replace_names=["x", "y", "s", "linewidths",
                c, edgecolors, kwargs, x.size,
                get_next_color_func=self._get_patches_for_fill.get_next_color)

        if plotnonfinite and colors is None:
        if cmap and norm and not orig_edgecolor:
            # override edgecolor based on cmap and norm presence
            edgecolors = 'face'

        if plotnonfinite and (colors is None and edgecolors is None):
            c = np.ma.masked_invalid(c)
            x, y, s, linewidths = \
                cbook._combine_masks(x, y, s, linewidths)
        elif plotnonfinite and colors is None:
            c = np.ma.masked_invalid(c)
            x, y, s, edgecolors, linewidths = \
                cbook._combine_masks(x, y, s, edgecolors, linewidths)
        elif plotnonfinite and edgecolors is None:
            c = np.ma.masked_invalid(c)
            x, y, s, colors, linewidths = \
                cbook._combine_masks(x, y, s, colors, linewidths)
        else:
            x, y, s, c, colors, edgecolors, linewidths = \
                cbook._combine_masks(
            alpha=alpha,
        )
        collection.set_transform(mtransforms.IdentityTransform())
        if colors is None:

        if ((colors is None or edgecolors is None) and not mcolors.is_color_like(c) and
                (not isinstance(c, np.ndarray) or isinstance(c, np.ma.MaskedArray))):
            collection.set_array(c)
            collection.set_cmap(cmap)
            collection.set_norm(norm)
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
     (dict(c='b', edgecolor='r', edgecolors='g'), 'r'),
     (dict(color='r'), 'r'),
     (dict(color='r', edgecolor='g'), 'g'),
     (dict(facecolors='none'), None),
     (dict(c='b', facecolors='none'), np.array([[0, 0, 1, 1]]))
     ])
 def test_parse_scatter_color_args_edgecolors(kwargs, expected_edgecolors):
    def get_next_color():
    _, _, result_edgecolors = \
        mpl.axes.Axes._parse_scatter_color_args(
            c, edgecolors, kwargs, xsize=2, get_next_color_func=get_next_color)
    assert result_edgecolors == expected_edgecolors
    if isinstance(expected_edgecolors, np.ndarray):
        assert_allclose(result_edgecolors, expected_edgecolors)
    else:
        assert result_edgecolors == expected_edgecolors


 def test_parse_scatter_color_args_error():
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,15 @@
		Enable configuration of empty markers in `~matplotlib.axes.Axes.scatter`
		------------------------------------------------------------------------

		`~matplotlib.axes.Axes.scatter` can now be configured to plot empty markers by setting ``facecolors`` to 'none' and defining ``c``. In this case, ``c`` will be now used as ``edgecolor``.

		.. plot::
		:include-source: true
		:alt: A simple scatter plot which illustrates the use of the scatter function to plot empty markers.

		import numpy as np
		import matplotlib.pyplot as plt

		x = np.arange(0, 10)
		plt.scatter(x, x, c=x, facecolors='none', marker='o')
		plt.show()
Original file line number	Diff line number	Diff line change
Expand Up		@@ -2749,6 +2749,8 @@ def get_next_color():
		(dict(c='b', edgecolor='r', edgecolors='g'), 'r'),
		(dict(color='r'), 'r'),
		(dict(color='r', edgecolor='g'), 'g'),
		(dict(facecolors='none'), None),
		(dict(c='b', facecolors='none'), np.array([[0, 0, 1, 1]]))
Copy link Member tacaswellMar 13, 2024 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. I think we need to cover the case of colormapping + empty here as well.
		])
		def test_parse_scatter_color_args_edgecolors(kwargs, expected_edgecolors):
		def get_next_color():
Expand All		@@ -2759,7 +2761,10 @@ def get_next_color():
		_, _, result_edgecolors = \
		mpl.axes.Axes._parse_scatter_color_args(
		c, edgecolors, kwargs, xsize=2, get_next_color_func=get_next_color)
		assert result_edgecolors == expected_edgecolors
		if isinstance(expected_edgecolors, np.ndarray):
		assert_allclose(result_edgecolors, expected_edgecolors)
		else:
		assert result_edgecolors == expected_edgecolors


		def test_parse_scatter_color_args_error():
Expand Down