Save plot to numpy array
matplotlib, numpy, python
Solution
This is a handy trick for unit tests and the like, when you need to do a pixel-to-pixel comparison with a saved plot.
One way is to use `fig.canvas.tostring_rgb` and then `numpy.fromstring` with the approriate dtype. There are other ways as well, but this is the one I tend to use.
E.g.
import matplotlib.pyplot as plt
import numpy as np
# Make a random plot...
fig = plt.figure()
fig.add_subplot(111)
# If we haven't already shown or saved the plot, then we need to
# draw the figure first...
fig.canvas.draw()
# Now we can save it to a numpy array.
data = np.frombuffer(fig.canvas.tostring_rgb(), dtype=np.uint8)
data = data.reshape(fig.canvas.get_width_height()[::-1] + (3,))
Problem
In Python and Matplotlib, it is easy to either display the plot as a popup window or save the plot as a PNG file. How can I instead save the plot to a numpy array in RGB format?