Question

Matplotlib and Pylab don’t work in Python CGI. But the same combination is working in the Python shell.
Following is the code:

#!C:/Python26/python
import cgi
import cgitb
import sys
import os
cgitb.enable()

# set HOME environment variable to a directory the httpd server can write to
os.environ[ 'HOME' ] = '/tmp/'

import matplotlib
# chose a non-GUI backend
matplotlib.use( 'Agg' )

import pylab

#Deals with inputing data into python from the html form
form = cgi.FieldStorage()

# construct your plot
pylab.plot([1,2,3])

print "Content-Type: image/png\n"

# save the plot as a png and output directly to webserver
pylab.savefig( "test.png")

Answer 1

Your code is a little incomplete. As it stands you are writing the plot to a file on the servers hard-drive. You are not returning it to the browser. One method to do this is to save the plot to a StringIO object and then stream it back.

import cStringIO
imgData = cStringIO.StringIO()
pylab.savefig(imgData, format='png')

# rewind the data
imgData.seek(0)

print "Content-Type: image/png\n"
print

print imgData.read()