Merge pull request matplotlib#25044 from yuzie007/hexbin-lw

Modify `hexbin` to respect :rc:`patch.linewidth`

Author: rcomer

doc/api/next_api_changes/behavior/25044-YI.rst

@@ -0,0 +1,6 @@
+``hexbin`` now defaults to ``rcParams["patch.linewidth"]``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The default value of the *linewidths* argument of `.Axes.hexbin` has
+been changed from ``1.0`` to :rc:`patch.linewidth`. This improves the
+consistency with `.QuadMesh` in `.Axes.pcolormesh` and `.Axes.hist2d`.

lib/matplotlib/axes/_axes.py

@@ -4892,7 +4892,7 @@ def hexbin(self, x, y, C=None, gridsize=100, bins=None,
             The alpha blending value, between 0 (transparent) and 1 (opaque).
 
         linewidths : float, default: *None*
-            If *None*, defaults to 1.0.
+            If *None*, defaults to :rc:`patch.linewidth`.
 
         edgecolors : {'face', 'none', *None*} or color, default: 'face'
             The color of the hexagon edges. Possible values are:
@@ -5038,7 +5038,7 @@ def reduce_C_function(C: array) -> float
             [[.5, -.5], [.5, .5], [0., 1.], [-.5, .5], [-.5, -.5], [0., -1.]])
 
         if linewidths is None:
-            linewidths = [1.0]
+            linewidths = [mpl.rcParams['patch.linewidth']]
 
         if xscale == 'log' or yscale == 'log':
             polygons = np.expand_dims(polygon, 0) + np.expand_dims(offsets, 1)