Merge pull request #16060 from anntzer/pcolor_demo

timhoffm · web-flow · commit b83d9d64d760 · 2020-01-01T14:35:38.000+01:00
Cleanup pcolor_demo.
diff --git a/examples/images_contours_and_fields/pcolor_demo.py b/examples/images_contours_and_fields/pcolor_demo.py
@@ -36,18 +36,19 @@
 # Demonstrates similarities between `~.axes.Axes.pcolor`,
 # `~.axes.Axes.pcolormesh`, `~.axes.Axes.imshow` and
 # `~.axes.Axes.pcolorfast` for drawing quadrilateral grids.
+# Note that we call ``imshow`` with ``aspect="auto"`` so that it doesn't force
+# the data pixels to be square (the default is ``aspect="equal"``).
 
 # make these smaller to increase the resolution
 dx, dy = 0.15, 0.05
 
 # generate 2 2d grids for the x & y bounds
-y, x = np.mgrid[slice(-3, 3 + dy, dy),
-                slice(-3, 3 + dx, dx)]
-z = (1 - x / 2. + x ** 5 + y ** 3) * np.exp(-x ** 2 - y ** 2)
+y, x = np.mgrid[-3:3+dy:dy, -3:3+dx:dx]
+z = (1 - x/2 + x**5 + y**3) * np.exp(-x**2 - y**2)
 # x and y are bounds, so z should be the value *inside* those bounds.
 # Therefore, remove the last value from the z array.
 z = z[:-1, :-1]
-z_min, z_max = -np.abs(z).max(), np.abs(z).max()
+z_min, z_max = -abs(z).max(), abs(z).max()
 
 fig, axs = plt.subplots(2, 2)
 
@@ -64,8 +65,8 @@
 ax = axs[1, 0]
 c = ax.imshow(z, cmap='RdBu', vmin=z_min, vmax=z_max,
               extent=[x.min(), x.max(), y.min(), y.max()],
-              interpolation='nearest', origin='lower')
-ax.set_title('image (nearest)')
+              interpolation='nearest', origin='lower', aspect='auto')
+ax.set_title('image (nearest, aspect="auto")')
 fig.colorbar(c, ax=ax)
 
 ax = axs[1, 1]
@@ -84,7 +85,7 @@
 # The following shows pcolor plots with a log scale.
 
 N = 100
-X, Y = np.mgrid[-3:3:complex(0, N), -2:2:complex(0, N)]
+X, Y = np.meshgrid(np.linspace(-3, 3, N), np.linspace(-2, 2, N))
 
 # A low hump with a spike coming out.
 # Needs to have z/colour axis on a log scale so we see both hump and spike.
