From: Thomas Danckaert <thomas.danckaert@gmail.com>
Subject: bug#25834: [PATCH 5/7] gnu: python-matplotlib: Update to 2.0.0.
Date: Wed, 22 Feb 2017 12:22:51 +0100

> From: Thomas Danckaert <post@thomasdanckaert.be>
> 
> * gnu/packages/python.scm (python-matplotlib): Update to 2.0.0.
> [source]: Remove Tk backend patch, use Github instead of Sourceforge.
> [outputs]: Remove "doc" output.
> [propagated-inputs]: Add python-cycler.
> [native-inputs]: Remove python-sphinx, python-numpydoc, texlive and texinfo.
> (python-matplotlib-documentation, python2-matplotlib-documentation): New
> variable.
> * gnu/packages/patches/matplotlib-setupext-tk.patch: Delete file.
> * gnu/local.mk (dist_patch_DATA): Remove patch.

I send an updated patch because I've realized that we now have python-qt as well.  Adding python-qt enables the Qt5Agg backend (interactive plotting widget using Qt).

I'm not sure if it should be a propagated input, though.  With
python-qt as a regular input, the users have to install python-qt into
their profile if they want to use the Qt5Agg backend.  When you ask matplotlib to use Qt5Agg but don't have python-qt in your profile, you get the following error:

> ImportError: Matplotlib qt-based backends require an external PyQt4,
> PyQt5, or PySide package to be installed, but it was not found.

This is unlike the TkAgg backend (similar plotting widget using Tk), which is available immediately (I think because of the propagated python-tkinter).  Is this OK, or do we want to propagate python-qt as well so everything works immediately?

The GtkAgg backend seems work automatically when in Gnome shell, but not in xfce4 (and the error message is not helpful).  My guess is that something is missing from $GI_TYPELIB_PATH in xfce4.  In a Gnome session, $GI_TYPELIB_PATH contains a big list of entries, while in an xfce4, it only contains ${HOME}/.guix-profile/lib/girepository-1.0.

Thomas