Python xticks in subplots

There are two ways:

1. Use the axes methods of the subplot object (e.g. ax.set_xticks and ax.set_xticklabels) or
2. Use plt.sca to set the current axes for the pyplot state machine (i.e. the plt interface).

As an example (this also illustrates using setp to change the properties of all of the subplots):

import matplotlib.pyplot as plt

fig, axes = plt.subplots(nrows=3, ncols=4)

# Set the ticks and ticklabels for all axes
plt.setp(axes, xticks=[0.1, 0.5, 0.9], xticklabels=['a', 'b', 'c'],
        yticks=[1, 2, 3])

# Use the pyplot interface to change just one subplot...
plt.sca(axes[1, 1])
plt.xticks(range(3), ['A', 'Big', 'Cat'], color='red')

fig.tight_layout()
plt.show()

See the (quite) recent answer on the matplotlib repository, in which the following solution is suggested:

• If you want to set the xticklabels:

  ax.set_xticks([1,4,5]) 
  ax.set_xticklabels([1,4,5], fontsize=12)
  

• If you want to only increase the fontsize of the xticklabels, using the default values and locations (which is something I personally often need and find very handy):

  ax.tick_params(axis="x", labelsize=12) 
  

• To do it all at once:

  plt.setp(ax.get_xticklabels(), fontsize=12, fontweight="bold", 
           horizontalalignment="left")`