Add the "contour.linewidths" configuration option

stefraynaud · stefraynaud · commit dbc1fd1b1d86 · 2020-04-24T14:38:15.000+02:00
It defaults to None whcih makes it to fallback
to "lines.linewidth" option.
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
@@ -1257,7 +1257,10 @@ def _process_linewidths(self):
         linewidths = self.linewidths
         Nlev = len(self.levels)
         if linewidths is None:
-            tlinewidths = [(mpl.rcParams['lines.linewidth'],)] * Nlev
+            default_linewidth = mpl.rcParams['contour.linewidths']
+            if default_linewidth is None:
+                default_linewidth = mpl.rcParams['lines.linewidth']
+            tlinewidths = [(default_linewidth,)] * Nlev
         else:
             if not np.iterable(linewidths):
                 linewidths = [linewidths] * Nlev
@@ -1749,7 +1752,7 @@ def _initialize_x_y(self, z):
             however introduce rendering artifacts at chunk boundaries depending
             on the backend, the *antialiased* flag and value of *alpha*.
 
-        linewidths : float or sequence of float, default: :rc:`lines.linewidth`
+        linewidths : float or sequence of float
             *Only applies to* `.contour`.
 
             The line width of the contour lines.
@@ -1759,6 +1762,9 @@ def _initialize_x_y(self, z):
             If a sequence, the levels in ascending order will be plotted with
             the linewidths in the order specified.
 
+            Defaults to :rc:`contour.linewidths`. If this value is None,
+            it falls back to :rc:`lines.linewidth`.
+
         linestyles : {*None*, 'solid', 'dashed', 'dashdot', 'dotted'}, optional
             *Only applies to* `.contour`.
 
diff --git a/lib/matplotlib/rcsetup.py b/lib/matplotlib/rcsetup.py
@@ -1195,6 +1195,7 @@ def _convert_validator_spec(key, conv):
     # contour props
     'contour.negative_linestyle': ['dashed', _validate_linestyle],
     'contour.corner_mask':        [True, validate_bool],
+    'contour.linewidths':        [None, validate_float_or_None],
 
     # errorbar props
     'errorbar.capsize':      [0, validate_float],
diff --git a/lib/matplotlib/tests/test_contour.py b/lib/matplotlib/tests/test_contour.py
@@ -5,7 +5,7 @@
 from numpy.testing import assert_array_almost_equal
 import matplotlib as mpl
 from matplotlib.testing.decorators import image_comparison
-from matplotlib import pyplot as plt
+from matplotlib import pyplot as plt, rc_context
 from matplotlib.colors import LogNorm
 import pytest
 
@@ -375,3 +375,17 @@ def test_contour_uneven():
     ax = axs[1]
     cs = ax.contourf(z, levels=[2, 4, 6, 10, 20])
     fig.colorbar(cs, ax=ax, spacing='uniform')
+
+
+@pytest.mark.parametrize("rcll, rccl, fcl, expected", [
+    (1.23, None, None, 1.23),
+    (1.23, 4.24, None, 4.24),
+    (1.23, 4.24, 5.02, 5.02)
+])
+def test_contour_linewidths(rcll, rccl, fcl, expected):
+
+    with rc_context(rc={"lines.linewidth": rcll, "contour.linewidths": rccl}):
+        fig, ax = plt.subplots()
+        X = np.arange(4*3).reshape(4, 3)
+        cs = ax.contour(X, linewidths=fcl)
+        assert cs.tlinewidths[0][0] == expected
