Non-linear axes for imshow in matplotlib

Question

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

Answer 1

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())