matplotlib-users

[Matplotlib-users] Using pylab interface with Agg backend?

[<gre...@gm...>]

Hi guys,

Is this possible?  Specifically I'm trying implement something close
to this example:
http://matplotlib.sourceforge.net/examples/webapp_demo.py

But would like to be able to utilize code found in samples like this:
http://matplotlib.sourceforge.net/screenshots/pie_demo.py

Much thanks!

--=20
Gregory Pi=F1ero
Chief Innovation Officer
Blended Technologies
(www.blendedtechnologies.com)

Re: [Matplotlib-users] Using pylab interface with Agg backend?

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

>>>>> "Gregory" =3D=3D Gregory Pi=F1ero <gre...@gm...> writes:

    Gregory> Hi guys, Is this possible?  Specifically I'm trying
    Gregory> implement something close to this example:
    Gregory> http://matplotlib.sourceforge.net/examples/webapp_demo.py

    Gregory> But would like to be able to utilize code found in
    Gregory> samples like this:
    Gregory> http://matplotlib.sourceforge.net/screenshots/pie_demo.py

You just have to tell matplotlib to use Agg as your backend -- pylab
will respect the default backend, whether it is a GUI, Agg or PS.

There are several ways to choose the backend

  * make it permanent by setting your backend to 'Agg' in matplotlibrc

  * change it on a per script basis exterally by launching with the -d
    option

     > python myscript.py -dAgg
     > python myscript.py -dPS
     > python myscript.py -dGTKAgg

  * probably best for a web app, use the matplotlib "use directive".
    This must be done *before* importing pylab

    import matplotlib
    matplotlib.use('Agg')
    import pylab
    plot and save....

This is discussed at http://matplotlib.sf.net/backends.html

JDH

Re: [Matplotlib-users] Using pylab interface with Agg backend?

[<gre...@gm...>]

So my only remaining point of confusion is why wasn't the pylab
interface used in the demo here:
>     Gregory> http://matplotlib.sourceforge.net/examples/webapp_demo.py

Is it just a style choice?

Re: [Matplotlib-users] Using pylab interface with Agg backend?

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

>>>>> "Gregory" =3D=3D Gregory Pi=F1ero <gre...@gm...> writes:

    Gregory> So my only remaining point of confusion is why wasn't the
    Gregory> pylab interface used in the demo here:
    Gregory> http://matplotlib.sourceforge.net/examples/webapp_demo.py

    Gregory> Is it just a style choice?

pylab manages figures for you -- you want to be sure in an application
that creates many figures and saves them to images (like a web app)
that every figure that is created is closed

  fig =3D figure(1)

  ...later
  close(1)

In a production app like a web application server generating graphics,
often times you don't want any magic going on behind the hood, and
pylab's stateful management of figures, the current figure, and the
current axes grates on some people who like to have full control over
object creation and destruction.

So the webapp demo shows how to use the API to manage and use
figures.  It is mainly a style choice.

JDH

Re: [Matplotlib-users] Using pylab interface with Agg backend?

[<gre...@gm...>]

On 7/12/06, John Hunter <jdh...@ac...> wrote:
> In a production app like a web application server generating graphics,
> often times you don't want any magic going on behind the hood, and
> pylab's stateful management of figures, the current figure, and the
> current axes grates on some people who like to have full control over
> object creation and destruction.
>
> So the webapp demo shows how to use the API to manage and use
> figures.  It is mainly a style choice.

Thanks, I'm starting to understand.  So since I am making a web app, I
should be refering to the API reference instead of the screenshots
code:
http://matplotlib.sourceforge.net/screenshots.html

If correct here, I guess I locate the API in the user guide?  Is there
anything else I should be using as a reference?

-Greg

Re: [Matplotlib-users] Using pylab interface with Agg backend?

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

>>>>> "Gregory" =3D=3D Gregory Pi=F1ero <gre...@gm...> writes:

    Gregory> If correct here, I guess I locate the API in the user
    Gregory> guide?  Is there anything else I should be using as a
    Gregory> reference?

http://matplotlib.sourceforge.net/faq.html#OO

http://matplotlib.sourceforge.net/leftwich_tut.txt


JDH