For changing the “tick frequency” on x or y-axis in matplotlib you can explicitly set where you want to tick marks with plt.xticks. Below is an example that shows how to do it:-
plt.xticks(np.arange(min(x), max(x)+1, 1.0))
An example that illustrates the use of plt.xticks:-
import numpy as np
import matplotlib.pyplot as plt
x = [0,5,9,10,15]
y = [0,1,2,3,4]
plt.plot(x,y)
plt.xticks(np.arange(min(x), max(x)+1, 1.0))
plt.show()
The np.arange function was used in place of Python's range function just in case min(x) and max(x) are floats instead of ints.