I am generating 2D arrays on log-spaced axes (for instance, the x pixel coordinates are generated using logspace(log10(0.95), log10(2.08), n)
.
I want to
In my view, it is better to use pcolor
and regular (non-converted) x and y values. pcolor
gives you more flexibility and regular x and y axis are less confusing.
import pylab as plt
import numpy as np
from matplotlib.colors import LogNorm
from matplotlib.ticker import LogFormatterMathtext
x=np.logspace(1, 3, 6)
y=np.logspace(0, 2,3)
X,Y=np.meshgrid(x,y)
z = np.logspace(np.log10(10), np.log10(1000), 5)
Z=np.vstack((z,z))
im = plt.pcolor(X,Y,Z, cmap='gray', norm=LogNorm())
plt.axvline(100, color='red')
plt.xscale('log')
plt.yscale('log')
plt.colorbar(im, orientation='horizontal',format=LogFormatterMathtext())
plt.show()
As pcolor
is slow, a faster solution is to use pcolormesh
instead.
im = plt.pcolormesh(X,Y,Z, cmap='gray', norm=LogNorm())
Actually, it works fine. I'm confused.
Previously I was getting errors about "Images are not supported on non-linear axes" which is why I asked this question. But now when I try it, it works:
import matplotlib.pyplot as plt
import numpy as np
x = np.logspace(1, 3, 5)
y = np.linspace(0, 2, 3)
z = np.linspace(0, 1, 4)
Z = np.vstack((z, z))
plt.imshow(Z, extent=[10, 1000, 0, 1], cmap='gray')
plt.xscale('log')
plt.axvline(100, color='red')
plt.show()
This is better than pcolor()
and pcolormesh()
because