Force integer axis label ticks on Matplotlib

March 24, 2021

To make a Matlabplot figure axis have integer-only label ticks, use method like:

ax.yaxis.set_major_locator(MaxNLocator(integer=True))
# or
ax.xaxis.set_major_locator(MaxNLocator(integer=True))

A complete standalone example follows:

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

x = np.arange(0.1,10.5,0.1) # arbitrary data

fg = plt.figure(layout='constrained')
ax = fg.gca()
ax.plot(x)

ax.yaxis.set_major_locator(MaxNLocator(integer=True))

plt.show()

If too few ticks are displayed, as per the Matplotlib MaxNLocator, you must have “at least min_n_ticks integers…found within the view limits.” Set “MaxNLocator(nbins=5,integer=True)” or similar if the defaults aren’t forcing integer ticks.