"import pylab" in a python console flags error "No module named _tkagg"

This was working before a recent update to python-matplotlib a day or so ago. I'm now running 0.99.3-1ubuntu3 also

the _tkagg.so extension did not get built in the ubuntu3 revision:

debdiff python-matplotlib_0.99.3-1ubuntu3_amd64.deb python-matplotlib_0.99.3-1ubuntu2_amd64.deb
[The following lists of changes regard files as different if they have
different names, permissions or owners.]

Files in second .deb but not in first
-------------------------------------
-rw-r--r-- root/root /usr/lib/pyshared/python2.6/matplotlib/backends/_tkagg.so
-rw-r--r-- root/root /usr/lib/pyshared/python2.7/matplotlib/backends/_tkagg.so

Files in first .deb but not in second
-------------------------------------
-rw-r--r-- root/root /usr/share/doc/python-matplotlib/changelog.Debian.gz

Control files: lines which differ (wdiff format)
------------------------------------------------
Depends: python-cairo, python-dateutil, python-gobject, python-matplotlib-data (>= [-0.99.3-1ubuntu3),-] {+0.99.3-1ubuntu2),+} python-numpy (>= 1:1.3.0), python-pyparsing, python-tz, python (<< 2.8), python (>= 2.6), python-support (>= 0.90.0), libatk1.0-0 (>= [-1.12.4),-] {+1.29.3),+} libc6 (>= 2.4), libcairo2 (>= 1.2.4), libfontconfig1 (>= 2.8.0), libfreetype6 (>= 2.2.1), libgcc1 (>= 1:4.1.1), libgdk-pixbuf2.0-0 (>= [-2.22.0),-] {+2.21.6),+} libglib2.0-0 (>= [-2.12.0),-] {+2.16.0),+} libgtk2.0-0 (>= 2.8.0), libpango1.0-0 (>= 1.14.0), libpng12-0 (>= 1.2.13-4), libstdc++6 (>= 4.4.0), {+tcl8.5 (>= 8.5.0), tk8.5 (>= 8.5.0),+} zlib1g (>= 1:1.1.4)
Installed-Size: [-7996-] {+8244+}
Version: [-0.99.3-1ubuntu3-] {+0.99.3-1ubuntu2+}

build logs ubuntu3:
https://launchpadlibrarian.net/68241882/buildlog_ubuntu-natty-amd64.matplotlib_0.99.3-1ubuntu3_BUILDING.txt.gz
OPTIONAL BACKEND DEPENDENCIES
                libpng: 1.2.44
               Tkinter: no
                        * Using default library and include directories for
                        * Tcl and Tk because a Tk window failed to open.
                        * You may need to define DISPLAY for Tk to work so
                        * that setup can determine where your libraries are
                        * located. Tkinter present, but header files are not
                        * found. You may need to install development
                        * packages.

whereas ubuntu2:
https://launchpadlibrarian.net/58652824/buildlog_ubuntu-natty-amd64.matplotlib_tcl = Tkinter.Tcl()0.99.3-1ubuntu2_BUILDING.txt.gz
OPTIONAL BACKEND DEPENDENCIES
                libpng: 1.2.44
               Tkinter: Tkinter: 73770, Tk: 8.5, Tcl: 8.5

adding a build dependency on tk-dev for tkConfig.sh solves the issue

or adapt setupext to account for this change in tk8.5-dev

tk8.5 (8.5.9-2) unstable; urgency=low

  * Moved /usr/share/tcltk/tk8.5/tkConfig.sh back to the /usr/lib/tk8.5
    directory because it is architecture dependent.

Because the default configuration uses the TKAgg backend, it might be a good idea to include 'matplotlib/backends/_tkagg.so' file in the list of files that must exist. I am not familiar with debian build files, but with rpm build packages, one can specify files that should exist after the build, and an error will be thrown if it doesn't exist. This way, such a mistake gets caught before commiting the package to the repos.

A work around is to edit /etc/matplotlibrc and modify line 31 to a different backend, such as GTK or QT4.

Correction on the previous comment, I found that GTK did not work, however GTKAgg did.

Many many thanks for this workaround! I hope the fix is released soon as well.

Julian,

Thank you for your patch. Looks good to me. I;'ll be uploading.

I also saw that you forwarded this patch upstream. Thank you for doing so.

Regards,

This bug was fixed in the package matplotlib - 0.99.3-1ubuntu4

---------------
matplotlib (0.99.3-1ubuntu4) natty; urgency=low

  * add patch 70_search_new_tkdir.patch
    + search in new path for tkConfig.sh, changed in tk 8.5.9-2 (LP: #752647)
 -- Julian Taylor <email address hidden> Thu, 07 Apr 2011 21:12:50 +0200

Thank you very very much for the fix!!! :)

Same problem seems to be back for upgrade to Precise. Should I file a new bug?

Seems to work for me... Here's the relevant portion from a python -v shell and import pylab:

import matplotlib.backends # directory /usr/lib/pymodules/python2.7/matplotlib/backends
# /usr/lib/pymodules/python2.7/matplotlib/backends/__init__.pyc matches /usr/lib/pymodules/python2.7/matplotlib/backends/__init__.py
import matplotlib.backends # precompiled from /usr/lib/pymodules/python2.7/matplotlib/backends/__init__.pyc
# /usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.pyc matches /usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.py
import matplotlib.backends.backend_tkagg # precompiled from /usr/lib/pymodules/python2.7/matplotlib/backends/backend_tkagg.pyc
# /usr/lib/python2.7/lib-tk/Tkinter.pyc matches /usr/lib/python2.7/lib-tk/Tkinter.py
import Tkinter # precompiled from /usr/lib/python2.7/lib-tk/Tkinter.pyc
dlopen("/usr/lib/python2.7/lib-dynload/_tkinter.so", 2);
import _tkinter # dynamically loaded from /usr/lib/python2.7/lib-dynload/_tkinter.so
# /usr/lib/python2.7/lib-tk/Tkconstants.pyc matches /usr/lib/python2.7/lib-tk/Tkconstants.py
import Tkconstants # precompiled from /usr/lib/python2.7/lib-tk/Tkconstants.pyc
# /usr/lib/python2.7/lib-tk/FileDialog.pyc matches /usr/lib/python2.7/lib-tk/FileDialog.py
import FileDialog # precompiled from /usr/lib/python2.7/lib-tk/FileDialog.pyc
# /usr/lib/python2.7/lib-tk/Dialog.pyc matches /usr/lib/python2.7/lib-tk/Dialog.py
import Dialog # precompiled from /usr/lib/python2.7/lib-tk/Dialog.pyc
# /usr/lib/pymodules/python2.7/matplotlib/backends/tkagg.pyc matches /usr/lib/pymodules/python2.7/matplotlib/backends/tkagg.py
import matplotlib.backends.tkagg # precompiled from /usr/lib/pymodules/python2.7/matplotlib/backends/tkagg.pyc
dlopen("/usr/lib/pymodules/python2.7/matplotlib/backends/_tkagg.so", 2);
import matplotlib.backends._tkagg # dynamically loaded from /usr/lib/pymodules/python2.7/matplotlib/backends/_tkagg.so
# /usr/lib/pymodules/python2.7/matplotlib/backends/backend_agg.pyc matches /usr/lib/pymodules/python2.7/matplotlib/backends/backend_agg.py
import matplotlib.backends.backend_agg # precompiled from /usr/lib/pymodules/python2.7/matplotlib/backends/backend_agg.pyc
dlopen("/usr/lib/pymodules/python2.7/matplotlib/backends/_backend_agg.so", 2);
import matplotlib.backends._backend_agg # dynamically loaded from /usr/lib/pymodules/python2.7/matplotlib/backends/_backend_agg.so
# /usr/lib/pymodules/python2.7/matplotlib/backends/windowing.pyc matches /usr/lib/pymodules/python2.7/matplotlib/backends/windowing.py
import matplotlib.backends.windowing # precompiled from /usr/lib/pymodules/python2.7/matplotlib/backends/windowing.pyc

works fine here to using the TkAgg backend. _tkagg.so is also there so its a different issue.
please check if its not a local installation interfering and open a new bug with ubuntu-bug and add more information like the stack trace, the used backend, python -v -c "import pylab" output etc.