Matplotlib savefig into different pages of a PDF

Question

I have a lengthy plot, composed o several horizontal subplots organized into a column.

When I call fig.savefig(\'what.pdf\'), the resulting output file shows all the

Answer 1

I suspect that there is a more elegant way to do this, but one option is to use tempfiles or StringIO to avoid making traditional files on the system and then you can piece those together.

Answer 2

I was wondering how to perform a similar thing. I have a set plots coming from different image files, which vary depending on the file. So the idea is, once I found a nice number of plots that can be plotted in a page, apply this for the files. Luckly, I found a solution suggested here: http://blog.marmakoide.org/?p=94. However it does not work correctly, since it only plots the first panel plots, leaving the rest of the panels empty. I modified it and here I include a working version for a (1XN) grid and the output plots.

import numpy

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

# Generate the data
data = numpy.random.randn(7, 1024)

# The PDF document
pdf_pages = PdfPages('histograms.pdf')

# Generate the pages
nb_plots = data.shape[0]
nb_plots_per_page = 5
nb_pages = int(numpy.ceil(nb_plots / float(nb_plots_per_page)))
grid_size = (nb_plots_per_page, 1)

for i, samples in enumerate(data):
  print
  print i,i % nb_plots_per_page,samples
  # Create a figure instance (ie. a new page) if needed
  if i % nb_plots_per_page == 0:
    print 'Opening'
    fig = plot.figure(figsize=(8.27, 11.69), dpi=100)
  # Close the page if needed
  elif (i + 1) % nb_plots_per_page == 0 or (i + 1) == nb_plots:
    plot.subplot2grid(grid_size, (i % nb_plots_per_page, 0))
    plot.hist(samples, 32, normed=1, facecolor='#808080', alpha=0.75)
    plot.title(str(i+1))

    plot.tight_layout()
    pdf_pages.savefig(fig)
    print 'Closing'
    print i,samples
    # Plot stuffs !
  print i,samples
  plot.subplot2grid(grid_size, (i % nb_plots_per_page, 0))
  plot.hist(samples, 32, normed=1, facecolor='#808080', alpha=0.75)
  plot.title(str(i+1))


# Write the PDF document to the disk
pdf_pages.close()
print 'histograms.pdf'

Answer 3

I haven't tried myself, but in the matplolib faq there are some instruction to save plots in pdf in several pages.

• FAQ http://matplotlib.org/faq/howto_faq.html#save-multiple-plots-to-one-pdf-file
• Example http://matplotlib.org/examples/pylab_examples/multipage_pdf.html