Can matplotlib add metadata to saved figures?

Question

I want to be able to ascertain the provenance of the figures I create using matplotlib, i.e. to know which version of my code and data created these figures. (See this essay for more on provenance.)

I imagine the most straightforward approach would be to add the revision numbers of the code and data to the metadata of the saved figures, or as comments in a postscript file for example.

Is there any easy way to do this in Matplotlib? The savefig function doesn't seem to be capable of this but has someone come up with a workable solution?

Answer 1

I don't know of a way using matplotlib, but you can add metadata to png's with PIL:

f = "test.png" METADATA = {"version":"1.0", "OP":"ihuston"}  # Create a sample image import pylab as plt import numpy as np X = np.random.random((50,50)) plt.imshow(X) plt.savefig(f)  # Use PIL to save some image metadata from PIL import Image from PIL import PngImagePlugin  im = Image.open(f) meta = PngImagePlugin.PngInfo()  for x in METADATA:     meta.add_text(x, METADATA[x]) im.save(f, "png", pnginfo=meta)  im2 = Image.open(f) print im2.info 

This gives:

{'version': '1.0', 'OP': 'ihuston'} 

Answer 2

If you are interested in PDF files, then you can have a look at the matplotlib module matplotlib.backends.backend_pdf. At this link there is a nice example of its usage, which could be "condensed" into the following:

import pylab as pl import numpy as np from matplotlib.backends.backend_pdf import PdfPages  pdffig = PdfPages('figure.pdf')  x=np.arange(10)  pl.plot(x) pl.savefig(pdffig, format="pdf")  metadata = pdffig.infodict() metadata['Title'] = 'Example' metadata['Author'] = 'Pluto' metadata['Subject'] = 'How to add metadata to a PDF file within matplotlib' metadata['Keywords'] = 'PdfPages example'  pdffig.close()