import numpy as np
import matplotlib.pyplot as plt
# set up plot style
plt.rc('xtick.minor', size=15)  # minor ticks extra long so they're obvious
plt.rc('xtick', top=False)      # should be no ticks at top (major or minor)
# plot data
data = np.random.rand(100).reshape(10, 10)
fig, ax = plt.subplots(1, 1)
ax.imshow(data)
# customize tick locations
ax.set_xticks(np.arange(10)[1::2], minor=False)  # this respects top=False
ax.set_xticks(np.arange(10)[::2], minor=True)  # this does not