How to add a grid line at a specific location in matplotlib plot?

Question

How do I add grid at a specific location on the y axis in a matplotlib plot?

Answer 1

Yes. It's very simple. Use the set_[x|y]ticks methods of axes object and toggle the grid as normal:

import matplotlib.pyplot as plt fig, ax = plt.subplots() ax.set_yticks([0.2, 0.6, 0.8], minor=False) ax.set_yticks([0.3, 0.55, 0.7], minor=True) ax.yaxis.grid(True, which='major') ax.yaxis.grid(True, which='minor') plt.show() 

Answer 2

If you only want to put in a line or two you can use

ax.axhline(y, linestyle='--', color='k') # horizontal lines ax.axvline(x, linestyle='--', color='k') # vertical lines 

with line style and color (or all the rest of line/artist properties) set to what ever you want