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matplotlib backends

The matplotlib core graphics routines interact with an abstract renderer and graphics context to allow device independent ouput. Currently, output to pygtk, wxPython, Tkinter, postscript, pdf, svg, agg (antigrain geometry) and Cairo are supported. With not too much effort, you can port matplotlib to your favorite display. If you are interested in porting to one of these platforms, please contact the matplotlib-devel mailing list.

Comparison of backends

The following table enumerates the capabilities of the different backends.

  output formats rotated text mathtext usetex alpha-blending arbitrary clipping
(polar plots) 		images
Agg png, raw X X X X X X
Cairo pdf, png,ps, svg, svgz X X       X
CocoaAgg png, raw X X X X X X
Emf emf ?   ? ? ? ?
FltkAgg png, raw X X X X X X
Gtk (Gdk) jpeg, png, raw   X       X
GtkAgg jpeg, png, raw X X X X X X
GtkCairo jpeg, pdf, png, ps, svg, svgz X X       X
Pdf pdf X X X X X X
Ps eps,ps X X X     X
QtAgg png,raw X X X X X X
Qt4Agg png,raw X X X X X X
Svg svg, svgz X X   X   X
TkAgg png,raw X X X X X X
Wx bmp, jpeg, pcx, png, raw, tiff, xpm            
WxAgg png,raw X X X X X X

In addition to these factors, there are other factors that may affect your backend selection:

Choosing a backend

You can choose your default backend in the matplotlibrc file, using the 'backend' option. The default can be overridden from the command line prompt. This allows most if not all matplotlib scripts to generate output to any of the backends without any alterations. Following the lead of the matlab print command, the backend can be chosen from the command line with the -d flag, as in 
# the GUI backends
> python subplot_demo.py -dGTK      # GTK GUI with gdk drawing
> python subplot_demo.py -dGTKAgg   # GTK GUI with antigrain rendering
> python subplot_demo.py -dGTKCairo # GTK GUI with Cairo rendering
> python subplot_demo.py -dTkAgg    # Tkinter GUI with antigrain rendering
> python subplot_demo.py -dWX       # WX backend
> python subplot_demo.py -dWXAgg    # WX GUI with antigrain rendering

# The image backends, no window pops up; you must call savefig
> python subplot_demo.py -dAgg     # antigrain geometry backend image
> python subplot_demo.py -dCairo   # Cairo backend
> python subplot_demo.py -dPS      # postscript backend
> python subplot_demo.py -dPDF     # pdf backend
> python subplot_demo.py -dSVG     # SVG backend
For backends that do not have a GUI, no output will be produced unless a call to savefig is made. The recommended way to use the savefig function is to not give an extension. The backends will choose the proper extension. This allows you to write a single script and select the output format from the command line. So a script containing savefig('somefile') will create somefile.ps if called with -dPS and somefile.png if called with -dAgg, and so on.

Alternatively, you can select the backend renderer in your script by calling the matplotlib use function. At the top of your script (before you import matplotlib.pylab, just do, for example 

import matplotlib
matplotlib.use('PS')
The current backend strings that are supported are Agg, Cairo, FltkAgg, GTK, GTKAgg, GTKCairo, PS, PDF, SVG, TkAgg, WX, WXAgg, Template. The default is GTKAgg. Template is a do nothing backend that serves as a template for backend writers (volunteers welcome!).

To get the most of your backend of choice, you may need to set an environment variable controlling the fonts; see fonts for more information.

Backend requirements

Each of the backends have a different set of requirements, listed below. All require numpy modules. Specific information for installing the other backends can be found on this page below or by clicking

Agg

 The antigrain geometry library is a platform independent library that provides efficient antialiased rendering with a vector model. Because it doesn't depend on a GUI framework, it is suitable for use in web application servers generating images for html inclusion or for generating images in batch scripts. Agg can also be embedded in GUI applications, as in the GTKAgg and TkAgg backends -- see setup.py

matplotlib includes its own copy of Agg. It does not need to be installed separately, even if compiling matplotlib from source.

Cairo

Cairo is a vector graphics library designed to provide high-quality display and print output. It doesn't depend on a GUI framework and is suitable for use in web application servers generating images for html inclusion or for generating images in batch scripts. Cairo can also be embedded in GUI applications, as in the GTKCairo backend

It requires pycairo version 0.5.0 or higher from Cairo downloads

GTK

This was the first backend supported by matplotlib; it requires

Windows GTK Quickstart

These install instructions will provide the GTK and GTKAgg backends on windows. If you encounter troubles, please see the FAQ

WX

 Requires wxpython. Windows users may want to consider the enthought edition of python, which comes with wxpython and numpy built in, so matplotlib will work right out of the box. matplotlib under WX has been tested on linux, win32 and OSX.

WXAgg

Requires wxpython. Windows users may want to consider the enthought edition of python, which comes with wxpython and numpy built in, so matplotlib will work right out of the box. matplotlib under WXAgg has been tested on linux, win32 and OSX.

GTKAgg: GTK GUI with antigrain rendering

GTK has a very nice and portable widget set. The gdk drawing commands, while fast, are somewhat limited. To overcome this limitation, GTKAgg marries the widgets of GTK with the rendering of antigrain. You need the agg and gtk prerequisites. Agg is builtin, so you only need to install pygtk and the GTK runtime, as described in gtk.

GTKCairo

 GTKCairo uses Cairo rendering from within the GTK GUI. You need the Cairo and gtk prerequisites.

Tkinter GUI backend

 Todd Miller has written a backend for Tkinter that uses the agg backend for rendering. To use Tkagg, you need to set the BUILD_TKAGG flag in setup.py. The windows installer comes with TkAgg prebuilt. See agg backend for more information on agg rendering and fonts. NOTE: on at least some versions of redhat linux, you must install a separate tkinter package, apparently tkinter-2.2.2-26.i386.rpm on Red Hat 9 linux. Alternately, Python built from source code (Python.org tarball, not the redhat SRPM) includes Tkinter support by default on Red Hat Linux. In general, TkAgg is known to work with TkAgg is known not work with: Both of the latter shells fail with a RuntimeError "abnormal program termination". I checked on www.python.org about Tkinter and Pythonwin and they're known not to work together so that explains TkAgg on Pythonwin. tkinter trouble.

I also looked into SciTE a little and discovered that it is related to Scintilla which in turn was derived from Pythonwin. scintilla This indicates to me that the same problem with Tkinter may be affecting both (SciTE and Pythonwin)... but I am out on a limb.

Postscript

The only requirement is numpy.

See the fonts page for more information about getting the postscript backend setup for proper font rendering; notably, you must make sure there are some '*.afm' files in your AFMPATH if you want to use fonts other than the ones that ship with matplotlib.

PDF

The only requirement is numpy.

SVG

The only requirement is numpy.

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