[IPython-dev] problems with ipython qtconsole --pylab on arch linux

Mark Andrews mjandrews.net at gmail.com
Thu Jan 29 18:59:49 EST 2015

After a recent upgrade on arch linux (where I have been using ipython for
years), I just encountered the following problem when I start ipython
(2.3.1) with "ipython2 qtconsole --pylab"

Using matplotlib backend: Qt5Agg

ERROR:tornado.application:Exception in callback <functools.partial object
at 0x7fcac006c838>

Traceback (most recent call last):

File "/usr/lib/python2.7/site-packages/tornado/ioloop.py", line 565, in

ret = callback()

File "/usr/lib/python2.7/site-packages/tornado/stack_context.py", line 275,
in null_wrapper

return fn(*args, **kwargs)

File "/usr/lib/python2.7/site-packages/IPython/kernel/zmq/ipkernel.py",
line 262, in enter_eventloop


File "/usr/lib/python2.7/site-packages/IPython/kernel/zmq/eventloops.py",
line 71, in loop_qt5

return loop_qt4(kernel)

File "/usr/lib/python2.7/site-packages/IPython/kernel/zmq/eventloops.py",
line 60, in loop_qt4

kernel.app = get_app_qt4([" "])

File "/usr/lib/python2.7/site-packages/IPython/lib/guisupport.py", line
111, in get_app_qt4

from IPython.external.qt_for_kernel import QtGui

File "/usr/lib/python2.7/site-packages/IPython/external/qt_for_kernel.py",
line 84, in <module>

from IPython.external.qt import QtCore, QtGui, QtSvg, QT_API

File "/usr/lib/python2.7/site-packages/IPython/external/qt.py", line 17, in


RuntimeError: Invalid Qt API 'pyqt5', valid values are: 'pyside', 'pyqt'

If I start with "ipython2 qtconsole" and then do

%matplotlib inline

import matplotlib.pyplot

then plotting works fine.

I am guessing that this is something that arises only with arch, and has
something to do with its packages for python Qt bindings.

Here are some of other relevant packages I am using

python2-matplotlib 1.4.2-3

python2-pyqt4 4.11.3-1
python2-pyqt5 5.4.0-2

It is not a major hassle but it would be good know what is causing this.


ps. ipython2 is arch linux's name for ipython 2.x, while the name ipython
is for ipython 3.x.
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