Matplotlib : Comma separated number format for axis

Question

I am attempting to change the format of my axis to be comma seperated in Matplotlib running under Python 2.7 but am unable to do so.

I suspect that I need to use a FuncFormatter but I am at a bit of a loss.

Can anyone help?

Answer 1

Yes, you can use matplotlib.ticker.FuncFormatter to do this.

Here is the example:

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

def func(x, pos):  # formatter function takes tick label and tick position
    s = str(x)
    ind = s.index('.')
    return s[:ind] + ',' + s[ind+1:]   # change dot to comma

y_format = tkr.FuncFormatter(func)  # make formatter

x = np.linspace(0,10,501)
y = np.sin(x)
ax = plt.subplot(111)
ax.plot(x,y)
ax.yaxis.set_major_formatter(y_format)  # set formatter to needed axis

plt.show()

This results in the following plot: