DOC: add fixed-aspect colorbar examples

jklymak · jklymak · commit 166c57823902 · 2021-02-14T17:16:23.000-08:00
diff --git a/examples/subplots_axes_and_figures/colorbar_placement.py b/examples/subplots_axes_and_figures/colorbar_placement.py
@@ -53,6 +53,47 @@
 fig.colorbar(pcm, ax=[axs[0, 2]], location='bottom')
 fig.colorbar(pcm, ax=axs[1:, :], location='right', shrink=0.6)
 fig.colorbar(pcm, ax=[axs[2, 1]], location='left')
+plt.show()
+
+######################################################################
+# Colorbars with fixed-aspect-ratio axes
+# ======================================
+#
+# Placing colorbars for axes with a fixed aspect ratio pose a particular
+# challenge as the parent axes changes size depending on the data view.
+
+fig, axs = plt.subplots(2, 2,  constrained_layout=True)
+cmaps = ['RdBu_r', 'viridis']
+for col in range(2):
+    for row in range(2):
+        ax = axs[row, col]
+        pcm = ax.pcolormesh(np.random.random((20, 20)) * (col + 1),
+                            cmap=cmaps[col])
+        if col == 0:
+            ax.set_aspect(2)
+        else:
+            ax.set_aspect(1/2)
+        if row == 1:
+            fig.colorbar(pcm, ax=ax, shrink=0.6)
+plt.show()
 
+######################################################################
+# One way around this issue is to use an `.Axes.inset_axes` to locate the
+# axes in axes co-ordinates.  Note that if you zoom in on the axes, and
+# change the shape of the axes, the colorbar will also change position.
 
+fig, axs = plt.subplots(2, 2, constrained_layout=True)
+cmaps = ['RdBu_r', 'viridis']
+for col in range(2):
+    for row in range(2):
+        ax = axs[row, col]
+        pcm = ax.pcolormesh(np.random.random((20, 20)) * (col + 1),
+                            cmap=cmaps[col])
+        if col == 0:
+            ax.set_aspect(2)
+        else:
+            ax.set_aspect(1/2)
+        if row == 1:
+            cax = ax.inset_axes([1.04, 0.2, 0.05, 0.6], transform=ax.transAxes)
+            fig.colorbar(pcm, ax=ax, cax=cax)
 plt.show()
