python - Scientific notation colorbar in matplotlib

Question

I am trying to put a colorbar to my image using matplotlib. The issue comes when I try to force the ticklabels to be written in scientific notation. How can I force the scientific notation (ie, 1x10^0, 2x10^0, ..., 1x10^2, and so on) in the ticks of the color bar?

Example, let's create and plot and image with its color bar:

import matplotlib as plot
import numpy as np

img = np.random.randn(300,300)
myplot = plt.imshow(img)
plt.colorbar(myplot)
plt.show()

When I do this, I get the following image:

However, I would like to see the ticklabels in scientific notation... Is there any one line command to do this? Otherwise, is there any hint out there? Thanks!

Answer 1

You could use colorbar's format parameter:

import matplotlib.pyplot as plt
import numpy as np
import matplotlib.ticker as ticker

img = np.random.randn(300,300)
myplot = plt.imshow(img)

def fmt(x, pos):
    a, b = '{:.2e}'.format(x).split('e')
    b = int(b)
    return r'${} imes 10^{{{}}}$'.format(a, b)

plt.colorbar(myplot, format=ticker.FuncFormatter(fmt))
plt.show()