Feature request: auto locate minor ticks on log scaled color bar #7141
Description
Matplotlib version 1.5.1, Python version 2.7.6 (Enthought Canopy) and OSX
As detailed in this stack overflow post, you have to explicitly specify the minor tick locations on a log scaled color bar. It would be nice if matplotlib would do this for you, instead of having to call minorticks = p.norm(np.hstack([np.arange(2, 10, 1)/10.0, np.arange(2, 10, 1)/1.0]) in the code below
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.colors import LogNorm
x = np.linspace(1,10,10)
y = np.linspace(1,10,10)
X, Y = np.meshgrid(x,y)
Z = np.abs(np.cos(X**2 - Y**2) * X**2 * Y)
f, ax = plt.subplots()
p = plt.pcolormesh(X, Y, Z, norm=LogNorm(), vmin=1e-2, vmax=1e2)
cb = plt.colorbar(p, ax=ax, orientation='horizontal', aspect=10)
# We need to nomalize the tick locations so that they're in the range from 0-1...
minorticks = p.norm(np.hstack([np.arange(2, 10, 1)/10.0, np.arange(2, 10, 1)/1.0]))
cb.ax.xaxis.set_ticks(minorticks, minor=True)
plt.show()