python - How to add a text into a Rectangle?

Question

I have a code that draws hundreds of small rectangles on top of an image :

The rectangles are instances of

    matplotlib.patches.Rectangle

I'd like to put a text (actually a number) into these rectangles, I don't see a way to do that. matplotlib.text.Text seems to allow one to insert text surrounded by a rectangle however I want the rectangle to be at a precise position and have a precise size and I don't think that can be done with text().

Answer 1

I think you need to use the annotate method of your axes object.

You can use properties of the rectangle to be smart about it. Here's a toy example:

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

fig, ax = plt.subplots()
rectangles = {'skinny' : mpatch.Rectangle((2,2), 8, 2),
              'square' : mpatch.Rectangle((4,6), 6, 6)}

for r in rectangles:
    ax.add_artist(rectangles[r])
    rx, ry = rectangles[r].get_xy()
    cx = rx + rectangles[r].get_width()/2.0
    cy = ry + rectangles[r].get_height()/2.0

    ax.annotate(r, (cx, cy), color='w', weight='bold', 
                fontsize=6, ha='center', va='center')

ax.set_xlim((0, 15))
ax.set_ylim((0, 15))
ax.set_aspect('equal')
plt.show()