Re: [matplotlib-devel] Re: [Matplotlib-users] Saving a figure to StringIO or similar

[John H. <jdh...@ac...>]

>>>>> "Robert" == Robert Kern <rk...@uc...> writes:

    Sascha> I am writing a web server app that creates charts among
    Sascha> other things. I am trying to get rid of the temporary file
    Sascha> that I use to transmit the figures created with matplotlib
    Sascha> to the actual web server. Although print_figure says "If
    Sascha> filename is a fileobject, write png to file object (thus
    Sascha> you can, for example, write the png to stdout)" I can't
    Sascha> successfully write anything to stdout. Anyone knows an
    Sascha> example or can give me some hint what I can do to get rid
    Sascha> of the tempfile?
    >>  Short answer: no known way to do this currently, though we'd
    >> like to figure it out.  As far as I know (and could very well
    >> be wrong) libpng requires a FILE*, which StringIO and cStringIO
    >> do not provide.

    Robert> StringIO isn't the issue here; being able to write to
    Robert> sys.stdout, which ought to have a valid FILE* underneath,
    Robert> is the issue.

Thanks for reminding me about this.  I thought it was possible to do
this, but had managed to forget

    import sys
    from pylab import plot, savefig, show
    plot([1,2,3])
    savefig(sys.stdout)
    show()

which I run with 

  > python test.py -dAgg > test.png

produces the expected figure.

JDH