Rework plot types quiver

timhoffm · timhoffm · commit 3bb3d840bf4a · 2021-09-27T22:28:22.000+02:00
While quiver can be used on individual points, the most common use case
is gridded data. We should use the common use case as the example.
Another reason is that, `quiver()` is assigned to the arrays category
in plot types.
diff --git a/plot_types/arrays/quiver.py b/plot_types/arrays/quiver.py
@@ -8,20 +8,21 @@
 import matplotlib.pyplot as plt
 import numpy as np
 
-plt.style.use('_mpl-gallery')
+plt.style.use('_mpl-gallery-nogrid')
 
 # make data
-phi = np.linspace(0, 2 * np.pi, 8)
-x, y = 4 + 1 * np.cos(phi), 4 + 1 * np.sin(phi)
-u, v = 1.5 * np.cos(phi), 1.5 * np.sin(phi)
+x = np.linspace(-4, 4, 6)
+y = np.linspace(-4, 4, 6)
+X, Y = np.meshgrid(x, y)
+U = X + Y
+V = Y - X
 
 # plot
 fig, ax = plt.subplots()
 
-ax.quiver(x, y, u, v, color="C0", angles='xy',
-          scale_units='xy', scale=0.5, width=.05)
+ax.quiver(X, Y, U, V, color="C0", angles='xy',
+          scale_units='xy', scale=5, width=.015)
 
-ax.set(xlim=(0, 8), xticks=np.arange(1, 8),
-       ylim=(0, 8), yticks=np.arange(1, 8))
+ax.set(xlim=(-5, 5), ylim=(-5, 5))
 
 plt.show()
