Use plt.rc_context for default styles (#7318)

* Use plt.rc_context for default styles

* Add tests

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Explain tests

* Check that args are prioritized

* Use rc_context as decorator

* Using as decorator is unfortunately not lazy, reverting

* Add test for facetgrid as well

* Update whats-new.rst

* Update whats-new.rst

* Update xarray/tests/test_plot.py

Co-authored-by: Mathias Hauser <mathause@users.noreply.github.com>

* import assert_no_warnings

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Joe Hamman <joe@earthmover.io>
Co-authored-by: Mathias Hauser <mathause@users.noreply.github.com>

Author: 4 people

doc/whats-new.rst

@@ -194,6 +194,9 @@ Bug fixes
   By `Michael Niklas <https://github.com/headtr1ck>`_.
 - Fix static typing of :py:meth:`xr.polyval` (:issue:`7312`, :pull:`7315`).
   By `Michael Niklas <https://github.com/headtr1ck>`_.
+- Fix matplotlib raising a UserWarning when plotting a scatter plot
+  with an unfilled marker (:issue:`7313`, :pull:`7318`).
+  By `Jimmy Westling <https://github.com/illviljan>`_.
 - Fix multiple reads on fsspec S3 files by resetting file pointer to 0 when reading file streams (:issue:`6813`, :pull:`7304`).
   By `David Hoese <https://github.com/djhoese>`_ and `Wei Ji Leong <https://github.com/weiji14>`_.
 - Fix :py:meth:`Dataset.assign_coords` resetting all dimension coordinates to default (pandas) index (:issue:`7346`, :pull:`7347`).

xarray/plot/dataarray_plot.py

@@ -52,6 +52,11 @@
     )
     from xarray.plot.facetgrid import FacetGrid
 
+_styles: MutableMapping[str, Any] = {
+    # Add a white border to make it easier seeing overlapping markers:
+    "scatter.edgecolors": "w",
+}
+
 
 def _infer_line_data(
     darray: DataArray, x: Hashable | None, y: Hashable | None, hue: Hashable | None
@@ -883,6 +888,8 @@ def newplotfunc(
         # All 1d plots in xarray share this function signature.
         # Method signature below should be consistent.
 
+        plt = import_matplotlib_pyplot()
+
         if subplot_kws is None:
             subplot_kws = dict()
 
@@ -894,6 +901,7 @@ def newplotfunc(
             allargs = locals().copy()
             allargs.update(allargs.pop("kwargs"))
             allargs.pop("darray")
+            allargs.pop("plt")
             allargs["plotfunc"] = globals()[plotfunc.__name__]
 
             return _easy_facetgrid(darray, kind="plot1d", **allargs)
@@ -973,24 +981,25 @@ def newplotfunc(
                 ckw = {vv: cmap_params[vv] for vv in ("vmin", "vmax", "norm", "cmap")}
                 cmap_params_subset.update(**ckw)
 
-        if z is not None:
-            if ax is None:
-                subplot_kws.update(projection="3d")
-            ax = get_axis(figsize, size, aspect, ax, **subplot_kws)
-            # Using 30, 30 minimizes rotation of the plot. Making it easier to
-            # build on your intuition from 2D plots:
-            ax.view_init(azim=30, elev=30, vertical_axis="y")
-        else:
-            ax = get_axis(figsize, size, aspect, ax, **subplot_kws)
-
-        primitive = plotfunc(
-            xplt,
-            yplt,
-            ax=ax,
-            add_labels=add_labels,
-            **cmap_params_subset,
-            **kwargs,
-        )
+        with plt.rc_context(_styles):
+            if z is not None:
+                if ax is None:
+                    subplot_kws.update(projection="3d")
+                ax = get_axis(figsize, size, aspect, ax, **subplot_kws)
+                # Using 30, 30 minimizes rotation of the plot. Making it easier to
+                # build on your intuition from 2D plots:
+                ax.view_init(azim=30, elev=30, vertical_axis="y")
+            else:
+                ax = get_axis(figsize, size, aspect, ax, **subplot_kws)
+
+            primitive = plotfunc(
+                xplt,
+                yplt,
+                ax=ax,
+                add_labels=add_labels,
+                **cmap_params_subset,
+                **kwargs,
+            )
 
         if np.any(np.asarray(add_labels)) and add_title:
             ax.set_title(darray._title_for_slice())
@@ -1233,9 +1242,6 @@ def scatter(
     hueplt: DataArray | None = kwargs.pop("hueplt", None)
     sizeplt: DataArray | None = kwargs.pop("sizeplt", None)
 
-    # Add a white border to make it easier seeing overlapping markers:
-    kwargs.update(edgecolors=kwargs.pop("edgecolors", "w"))
-
     if hueplt is not None:
         kwargs.update(c=hueplt.to_numpy().ravel())
 

xarray/tests/test_plot.py

@@ -30,6 +30,7 @@
 from xarray.tests import (
     assert_array_equal,
     assert_equal,
+    assert_no_warnings,
     requires_cartopy,
     requires_cftime,
     requires_matplotlib,
@@ -3204,3 +3205,38 @@ def test_facetgrid_axes_raises_deprecation_warning() -> None:
             ds = xr.tutorial.scatter_example_dataset()
             g = ds.plot.scatter(x="A", y="B", col="x")
             g.axes
+
+
+@requires_matplotlib
+def test_plot1d_default_rcparams() -> None:
+    import matplotlib as mpl
+
+    ds = xr.tutorial.scatter_example_dataset(seed=42)
+
+    with figure_context():
+        # scatter markers should by default have white edgecolor to better
+        # see overlapping markers:
+        fig, ax = plt.subplots(1, 1)
+        ds.plot.scatter(x="A", y="B", marker="o", ax=ax)
+        np.testing.assert_allclose(
+            ax.collections[0].get_edgecolor(), mpl.colors.to_rgba_array("w")
+        )
+
+        # Facetgrids should have the default value as well:
+        fg = ds.plot.scatter(x="A", y="B", col="x", marker="o")
+        ax = fg.axs.ravel()[0]
+        np.testing.assert_allclose(
+            ax.collections[0].get_edgecolor(), mpl.colors.to_rgba_array("w")
+        )
+
+        # scatter should not emit any warnings when using unfilled markers:
+        with assert_no_warnings():
+            fig, ax = plt.subplots(1, 1)
+            ds.plot.scatter(x="A", y="B", ax=ax, marker="x")
+
+        # Prioritize edgecolor argument over default plot1d values:
+        fig, ax = plt.subplots(1, 1)
+        ds.plot.scatter(x="A", y="B", marker="o", ax=ax, edgecolor="k")
+        np.testing.assert_allclose(
+            ax.collections[0].get_edgecolor(), mpl.colors.to_rgba_array("k")
+        )