matplotlib: how to draw a rectangle on image

Question

How to draw a rectangle on an image, like this:

import matplotlib.pyplot as plt
from PIL import Image
import numpy as np
im = np.array(Image.open(\'dog.png\'         


        

Answer 1

You need use patches.

import matplotlib.pyplot as plt
import matplotlib.patches as patches

fig2 = plt.figure()
ax2 = fig2.add_subplot(111, aspect='equal')

ax2.add_patch(
     patches.Rectangle(
        (0.1, 0.1),
        0.5,
        0.5,
        fill=False      # remove background
     ) ) 
fig2.savefig('rect2.png', dpi=90, bbox_inches='tight')