MNT: set the facecolor of nofill markers

tacaswell · tacaswell · commit 63d83daa10fb · 2020-07-06T23:01:08.000-04:00
Even though we are going to ignore it, set the facecolors to the user specified color and edgecolor to 'face' to maintain back-compatibility. We now warn if the user passes in an edgecolor that we ignore. closes #17849 partially reverts #17543 / d86cc2b
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -4451,7 +4451,8 @@ def scatter(self, x, y, s=None, c=None, marker=None, cmap=None, norm=None,
         s = np.ma.ravel(s)
         if len(s) not in (1, x.size):
             raise ValueError("s must be a scalar, or the same size as x and y")
-
+        # get the original edgecolor the user passed before we normalize
+        orig_edgecolor = edgecolors or kwargs.get('edgecolor', None)
         c, colors, edgecolors = \
             self._parse_scatter_color_args(
                 c, edgecolors, kwargs, x.size,
@@ -4480,6 +4481,14 @@ def scatter(self, x, y, s=None, c=None, marker=None, cmap=None, norm=None,
         path = marker_obj.get_path().transformed(
             marker_obj.get_transform())
         if not marker_obj.is_filled():
+            if orig_edgecolor is not None:
+                cbook._warn_external(
+                    f"You passed a edgecolor/edgecolors ({orig_edgecolor!r}) "
+                    f"for an unfilled marker ({marker!r}).  Matplotlib is "
+                    "ignoring the edge color in favor of the facecolor.  This "
+                    "behavior may change in the future."
+                )
+            edgecolors = 'face'
             if linewidths is None:
                 linewidths = rcParams['lines.linewidth']
             elif np.iterable(linewidths):
@@ -4491,8 +4500,8 @@ def scatter(self, x, y, s=None, c=None, marker=None, cmap=None, norm=None,
 
         collection = mcoll.PathCollection(
                 (path,), scales,
-                facecolors=colors if marker_obj.is_filled() else 'none',
-                edgecolors=edgecolors if marker_obj.is_filled() else colors,
+                facecolors=colors,
+                edgecolors=edgecolors,
                 linewidths=linewidths,
                 offsets=offsets,
                 transOffset=kwargs.pop('transform', self.transData),
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -1874,7 +1874,7 @@ def test_scatter_unfilled(self):
         coll = plt.scatter([0, 1, 2], [1, 3, 2], c=['0.1', '0.3', '0.5'],
                            marker=mmarkers.MarkerStyle('o', fillstyle='none'),
                            linewidths=[1.1, 1.2, 1.3])
-        assert coll.get_facecolors().shape == (0, 4)  # no facecolors
+        assert_array_equal(coll.get_edgecolors(), coll.get_facecolors())
         assert_array_equal(coll.get_edgecolors(), [[0.1, 0.1, 0.1, 1],
                                                    [0.3, 0.3, 0.3, 1],
                                                    [0.5, 0.5, 0.5, 1]])
@@ -6397,3 +6397,13 @@ def test_relative_ticklabel_sizes(size):
     for name, axis in zip(['x', 'y'], [ax.xaxis, ax.yaxis]):
         for tick in axis.get_major_ticks():
             assert tick.label1.get_size() == axis._get_tick_label_size(name)
+
+
+@pytest.mark.style('default')
+def test_warn_ignored_scatter_kwargs():
+    with pytest.warns(UserWarning,
+                      match=r"You passed a edgecolor/edgecolors"):
+
+        c = plt.scatter(
+            [0], [0], marker="+", s=500, facecolor="r", edgecolor="b"
+        )
