How to drawImage a matplotlib figure in a reportlab canvas?

Question

I would like to add a figure generated with matplotlib to a reportlab canvas using the method drawImage and without having to save the figure to the hard drive first.

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Answer 1

The problem is that drawImage expects either an ImageReader object or a filepath, not a file handle.

The following should work:

import Image
import matplotlib.pyplot as plt
import cStringIO
from reportlab.pdfgen import canvas
from reportlab.lib.units import inch, cm

from reportlab.lib.utils import ImageReader

fig = plt.figure(figsize=(4, 3))
plt.plot([1,2,3,4])
plt.ylabel('some numbers')

imgdata = cStringIO.StringIO()
fig.savefig(imgdata, format='png')
imgdata.seek(0)  # rewind the data

Image = ImageReader(imgdata)

c = canvas.Canvas('test.pdf')
c.drawImage(Image, cm, cm, inch, inch)
c.save()