[Matplotlib-users] Re: matplotlib, great module

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

>>>>> "Birger" ==   <bir...@te...> writes:

    Birger> Hi.  I stumbled over your matplotlib module, and it's
    Birger> exactly what I have been looking for being a long time
    Birger> matlab user.

    Birger> Since sourceforge is down, I have a question which I hope
    Birger> you'll answer, but I fully understand if you don't have
    Birger> the time

No problem, when it comes back up you may want to join the mailing
list

    Birger> (using GTK, latest version on winXP) creating a simple
    Birger> script like this:

    Birger> from matplotlib.matlab import * vector = [1, 2, 3, 4, 5,
    Birger> 3, 2, 1] plot(vec) savefig(r'c:\test.jpg')

    Birger> This does not save the file, but calling 'show()' will
    Birger> show the file and then save the file.  Shouldn't it be
    Birger> possible to save a fig without calling show? I have plans
    Birger> to use this in a cgi application, and hope I can do it
    Birger> this way.

There are three ways to do this currently.  Are you planning on
running your web server under windows or linux or other?  The platform
you are on will determine which route is easiest.

  1) On Linux/UNIX, Run matplotlib in a X virtual frame buffer (Xvfb)
     which is a virtual X windows.  There you can save the figures in
     the GTK backend with no window ever popping up.  I'm going to do
     some more investigating to see if pygtk is capable of drawing
     with no window in the absence of Xvfb (in which the window is
     simulated).  I am using matplotlib in a web application server so
     I can provide some example code.

  2) Alternatively, you can use the GD backend, which is designed to
     do offline drawing.  I haven't succeeded in getting gdmodule
     compiled for windows, but I know it's doable.  I just haven't
     pressed the issue because so far noone has wanted it.

  3) Finally, a hack solution which would work under windows is to use
     the ps backend to generate the plots (this requires only Numeric
     and produces high quality output) and use another module like PIL
     to convert them to PNG or JPG to serve over the web.  This is in
     my opinion the least desirable solution, but one you may want to
     consider if you must work on win32 and can't get GD running.  


    Birger> If I were better at programming, I would have written a
    Birger> PIL module for matplotlib, since matplotlib is a module I
    Birger> will use extensively in the future

I would like to have a PIL and python Tk backend.  So when you get
you're programming chops up to speed, definitely think of us!

John Hunter