Saving all open matplotlib figures in one file at once

Question

I am trying to save an arbitrary number of matplotlib figures that I have already created into 1 file(PDF?). Is there a way to do it with one command?

Answer 1

MatPlotLib currently supports saving multiple figures to a single pdf file. An implementation that uses this functionality would be:

from matplotlib.backends.backend_pdf import PdfPages
import matplotlib.pyplot as plt

def multipage(filename, figs=None, dpi=200):
    pp = PdfPages(filename)
    if figs is None:
        figs = [plt.figure(n) for n in plt.get_fignums()]
    for fig in figs:
        fig.savefig(pp, format='pdf')
    pp.close()

---

Example Usage

First create some figures,

import matplotlib.pyplot as plt
import numpy as np

fig1 = plt.figure()
plt.plot(np.arange(10))

fig2 = plt.figure()
plt.plot(-np.arange(3, 50), 'r-')

By default multipage will print all of the open figures,

multipage('multipage.pdf')

The only gotcha here is that all figures are rendered as vector (pdf) graphics. If you want your figure to utilize raster graphics (i.e. if the files are too large as vectors), you could use the rasterized=True option when plotting quantities with many points. In that case the dpi option that I included might be useful, for example:

fig3 = plt.figure()
plt.plot(np.random.randn(10000), 'g-', rasterized=True)

multipage('multipage_w_raster.pdf', [fig2, fig3], dpi=250)

In this example I have chosen to only print fig2 and fig3.