what's new

fmaussion · efiring · commit 3638d42cfb96 · 2020-05-28T11:58:47.000-10:00
diff --git a/doc/users/whats_new/extend_kwarg_to_BoundaryNorm.rst b/doc/users/whats_new/extend_kwarg_to_BoundaryNorm.rst
@@ -0,0 +1,41 @@
+New "extend" keyword to colors.BoundaryNorm
+-------------------------------------------
+
+:func:`~matplotlib.colors.BoundaryNorm` now has an ``extend`` kwarg. This is
+useful when creating a discrete colorbar from a continuous colormap: when
+setting ``extend`` to ``'both'``, ``'min'`` or ``'max'``, the colors are
+interpolated so that the extensions have a different color than the inner
+cells.
+
+Example
+```````
+::
+
+    from matplotlib import pyplot as plt
+    import matplotlib as mpl
+
+    # Make a figure and axes with dimensions as desired.
+    fig = plt.figure(figsize=(8, 3))
+    ax1 = fig.add_axes([0.05, 0.7, 0.9, 0.2])
+    ax2 = fig.add_axes([0.05, 0.2, 0.9, 0.2])
+
+    # Set the colormap and bounds
+    bounds = [-1, 2, 5, 7, 12, 15]
+    cmap = mpl.cm.get_cmap('viridis')
+
+    # Default behavior
+    norm = mpl.colors.BoundaryNorm(bounds, cmap.N)
+    cb1 = mpl.colorbar.ColorbarBase(ax1, cmap=cmap,
+                                         norm=norm,
+                                         extend='both',
+                                         orientation='horizontal')
+    cb1.set_label('Default BoundaryNorm ouput')
+
+    # New behavior
+    norm = mpl.colors.BoundaryNorm(bounds, cmap.N, extend='both')
+    cb2 = mpl.colorbar.ColorbarBase(ax2, cmap=cmap,
+                                         norm=norm,
+                                         orientation='horizontal')
+    cb2.set_label("With new extend='both' keyword")
+
+    plt.show()
