CODEWITHSUNDEEP
python-3.xmatplotlib
ritter
ritter

Reputation: 7709

Putting text from one corner to the opposite one

I'd like my plot to have a background text to be stretched from one corner (say lower left) to the opposite corner. The x and y dimensions are not isometric and it's not a square plot, so a fixed angle of 45 degrees will not work.

So far I have the text starting in the correct corner. How can the text be rotated and stretched so it spans the entire plot?

import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.add_subplot(1, 1, 1)

# plot command not shown

ax.text(ax.get_xlim()[0], ax.get_ylim()[0] , 'PRELIMINARY' , rotation=45  )

Upvotes: 0

Views: 77

Answers (1)

JohanC
JohanC

Reputation: 80349

To position something with respect to the subplot (the ax), it helps to work in axes coordinates. These go from 0,0 in the lower left to 1,1 in the top right. Putting the text at 0.5,0.5 would set it nicely centered.

To calculate the angle, one could divide the subplot's height in pixels by its width, then take the arc tangent, and convert from radians to degrees.

The optimal size for the text is harder to calculate. One would need to render it, measure it, change the font size and render it again. Or just manually try a few sizes until it looks OK.

Note that when the window size gets changed interactively, the text will stay nicely in the center, but the rotation will get a bit off.

import matplotlib.pyplot as plt
import numpy as np

fig = plt.figure()
ax = fig.add_subplot(1, 1, 1)

ax.text(0.5, 0.5, 'PRELIMINARY', transform=ax.transAxes, size=50,
        rotation=np.degrees(np.arctan(ax.get_window_extent().height / ax.get_window_extent().width)),
        ha='center', va='center')
plt.show()

text from bottom left to top right

Upvotes: 1

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