Log labels on colorbar matplotlib

python matplotlib colorbar imshow
Jbarrell picture Jbarrell · Dec 7, 2014 · Viewed 7.5k times · Source

I have a logarithmic imshow figure, and when the colorbar is created, its axis labels and ticks are logarithmic, but because of the short range (0-50) of the values, the colorbar looks like this:

enter image description here

and I would like it to instead show as 0, 5, 10, 20, 50 spaced along the axis (logarithmic spacing).

I can't seem to get this to work.

Thanks for any help.

Answer

hitzg picture hitzg · Dec 8, 2014

Use the LogFormatter class and set labelOnlyBase to False: 

import matplotlib.pyplot as plt
import numpy as np
import matplotlib.colors
from matplotlib.ticker import LogFormatter 

A = np.random.rand(50,50)*50
plt.imshow(A, norm=matplotlib.colors.LogNorm())
formatter = LogFormatter(10, labelOnlyBase=False) 
cb = plt.colorbar(ticks=[1,5,10,20,50], format=formatter)
plt.show()

Related questions

Set two matplotlib imshow plots to have the same color map scale

I am trying to plot to fields with the same scale. The upper image values are a 10 times higher than the one bellow, but they turn out to be the same color in the imshow. How can I set both …

Read More
Set Colorbar Range in matplotlib

I have the following code: import matplotlib.pyplot as plt cdict = { 'red' : ( (0.0, 0.25, .25), (0.02, .59, .59), (1., 1., 1.)), 'green': ( (0.0, 0.0, 0.0), (0.02, .45, .45), (1., .97, .97)), 'blue' : ( (0.0, 1.0, 1.0), (0.02, .75, .75), (1., 0.45, 0.45)) } cm = m.colors.LinearSegmentedColormap('my_colormap', cdict, 1024) plt.clf() plt.pcolor(X, Y, v, cmap=cm) plt.loglog() plt.xlabel('X Axis') plt.ylabel('Y Axis') …

Read More
matplotlib: colorbars and its text labels

I'd like to create a colorbar legend for a heatmap, such that the labels are in the center of each discrete color. Example borrowed from here: import matplotlib.pyplot as plt import numpy as np from matplotlib.colors import ListedColormap #…

Read More