Get Binary Image Data From a MatPlotLib Canvas?

Question

I'm trying to get the binary data from a matplotlib canvas so I can attach it to an email, but the only way I've found to do so is by saying:

filename = 'image.png'
canvas.print_figure(filename)
with open(filename, 'rb') as image:
    return image.read()

I'd really like to avoid the Disk IO since I don't need to hold onto the file afterwards.

Lior · Accepted Answer · 2012-08-27 15:43:52Z

6

Use a StringIO object as a file object, which can be given to the print_png canvas function.

from cStringIO import StringIO
sio = StringIO()
canvas.print_png(sio)
return sio.getvalue()

(if you're using Python 3, use io.BytesIO instead of cStringIO)

answered Aug 27, 2012 at 15:43

Lior

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4 Comments

Lior Over a year ago

Glad to help :) May I ask why do you need to access the raw png data of the canvas?

Subbarker Over a year ago

It's being attached to an email, and I couldn't see the need to keep around the files afterwards.

Lior Over a year ago

Oh, that's interesting. I would change the original question and add this explanation, so other people can search "email matplotlib plots" and find this question/answer.

Jorge González Lorenzo Over a year ago

Complete example using io.BytesIO: stackoverflow.com/questions/18766060/…

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