Backport PR #14062: Improve advanced quiver example

NelleV · MeeseeksDev[bot] · commit 1db5259f4f55 · 2019-04-27T20:35:16.000Z
diff --git a/examples/images_contours_and_fields/quiver_demo.py b/examples/images_contours_and_fields/quiver_demo.py
@@ -1,16 +1,17 @@
 """
-========================================================
-Demonstration of advanced quiver and quiverkey functions
-========================================================
+=======================================
+Advanced quiver and quiverkey functions
+=======================================
 
 Demonstrates some more advanced options for `~.axes.Axes.quiver`.  For a simple
 example refer to :doc:`/gallery/images_contours_and_fields/quiver_simple_demo`.
 
-Known problem: the plot autoscaling does not take into account the arrows, so
-those on the boundaries are often out of the picture.  This is *not* an easy
-problem to solve in a perfectly general way.  The workaround is to manually
-expand the Axes objects.
+Note: The plot autoscaling does not take into account the arrows, so
+those on the boundaries may reach out of the picture.  This is not an easy
+problem to solve in a perfectly general way.  The recommended workaround is to
+manually set the Axes limits in such a case.
 """
+
 import matplotlib.pyplot as plt
 import numpy as np
 
@@ -38,14 +39,16 @@
 
 ###############################################################################
 
+# sphinx_gallery_thumbnail_number = 3
+
 fig3, ax3 = plt.subplots()
 ax3.set_title("pivot='tip'; scales with x view")
 M = np.hypot(U, V)
 Q = ax3.quiver(X, Y, U, V, M, units='x', pivot='tip', width=0.022,
                scale=1 / 0.15)
 qk = ax3.quiverkey(Q, 0.9, 0.9, 1, r'$1 \frac{m}{s}$', labelpos='E',
                    coordinates='figure')
-ax3.scatter(X, Y, color='k', s=5)
+ax3.scatter(X, Y, color='0.5', s=1)
 
 plt.show()
 
