[Python-modules-team] Bug#752991: python3-matplotlib: pylab fails to be imported

[Martin Manns]

Package: python3-matplotlib
Version: 1.3.1-1+b2
Severity: grave
Justification: renders package unusable

Dear Maintainer,

When importing pylab then an ImportError is thrown (see below).
The pylab import is required by most matplotlib based programs.
I would expect the import to succeed without error.

Example:

$ python3 -c "import matplotlib.pylab"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python3/dist-packages/matplotlib/pylab.py", line 269, in
<module>
    from matplotlib.pyplot import *
  File "/usr/lib/python3/dist-packages/matplotlib/pyplot.py", line 98, in
<module>
    _backend_mod, new_figure_manager, draw_if_interactive, _show =
pylab_setup()
  File "/usr/lib/python3/dist-packages/matplotlib/backends/__init__.py", line
28, in pylab_setup
    globals(),locals(),[backend_name],0)
  File "/usr/lib/python3/dist-packages/matplotlib/backends/backend_tkagg.py",
line 11, in <module>
    import matplotlib.backends.tkagg as tkagg
  File "/usr/lib/python3/dist-packages/matplotlib/backends/tkagg.py", line 2,
in <module>
    from matplotlib.backends import _tkagg
ImportError: cannot import name '_tkagg'
$

The error does not occur with the python2 based package python-matplotlib on my
system:
$ python -c "import matplotlib.pylab"
$

This bug is probably related to #750630, which however addresses the package
python-matplotlib.

The workaround that is mentioned in #750630 works with the GTK3Cairo backend
but not with the GTK backend even though I do not see what dependency (i.e.
what Debian package) is missing:

$ python3 -c "import matplotlib;matplotlib.use('GTK3Cairo');import
matplotlib.pyplot as plt"
$

$ python3 -c "import matplotlib;matplotlib.use('GTK');import matplotlib.pyplot
as plt"
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/matplotlib/backends/backend_gtk.py",
line 12, in <module>
    import gobject
ImportError: No module named 'gobject'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python3/dist-packages/matplotlib/pyplot.py", line 98, in
<module>
    _backend_mod, new_figure_manager, draw_if_interactive, _show =
pylab_setup()
  File "/usr/lib/python3/dist-packages/matplotlib/backends/__init__.py", line
28, in pylab_setup
    globals(),locals(),[backend_name],0)
  File "/usr/lib/python3/dist-packages/matplotlib/backends/backend_gtk.py",
line 16, in <module>
    raise ImportError("Gtk* backend requires pygtk to be installed.")
ImportError: Gtk* backend requires pygtk to be installed.
$



-- System Information:
Debian Release: jessie/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing'), (500, 'oldstable')
Architecture: i386 (i686)

Kernel: Linux 3.14-1-686-pae (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages python3-matplotlib depends on:
ii  libc6                               2.19-4
ii  libfreetype6                        2.5.2-1
ii  libgcc1                             1:4.9.0-8
ii  libpng12-0                          1.2.50-1
ii  libstdc++6                          4.9.0-8
ii  python-matplotlib-data              1.3.1-1
ii  python3                             3.4.1-1
ii  python3-dateutil                    2.0+dfsg1-1
ii  python3-nose                        1.3.3-1
ii  python3-numpy [python3-numpy-abi9]  1:1.8.1-1+b1
ii  python3-pyparsing                   2.0.2+dfsg1-1
ii  python3-six                         1.7.2-1
ii  python3-tornado                     3.2.2-1
ii  python3-tz                          2012c-1

Versions of packages python3-matplotlib recommends:
pn  python3-imaging  <none>
ii  python3-tk       3.4.1-2

Versions of packages python3-matplotlib suggests:
ii  dvipng                        1.14-2
ii  ghostscript                   9.05~dfsg-8.1
ii  gir1.2-gtk-3.0                3.12.2-1+b1
ii  inkscape                      0.48.4-5
ii  ipython3                      2.1.0-1
ii  librsvg2-common               2.40.2-1
pn  python-matplotlib-doc         <none>
ii  python3-cairo                 1.10.0+dfsg-4+b1
ii  python3-gi [python3-gobject]  3.12.1-1+b1
ii  python3-pyqt4                 4.11+dfsg-2
ii  python3-scipy                 0.13.3-2+b1
ii  python3-sip                   4.16.1+dfsg-1
ii  texlive-extra-utils           2014.20140626-1
ii  texlive-latex-extra           2014.20140626-1
ii  ttf-staypuft                  0.04-6

-- no debconf information