Cannot Disable TkAgg Backend #7526
Description
Setup:
Matplotlib version 1.5.3 on FreeBSD 11 installed with pip
Problem:
I want to use matplotlib with only non-GUI backend AGG but it always installs with at least tkagg. This leads to problems when matplotlib cannot import _tkinter. I have created my own setup.cfg file and explicitly disabled all GUI backends including tkagg but matplotlib will still install tkagg. Note that the matplotlib setup.cfg documentation states that all GUI backends can be turned off.
env MPLSETUPCFG=./setup.cfg pip install matplotlib
...
OPTIONAL BACKEND EXTENSIONS
macosx: no [skipping due to configuration]
qt5agg: no [skipping due to configuration]
qt4agg: no [skipping due to configuration]
gtk3agg: no [skipping due to configuration]
gtk3cairo: no [skipping due to configuration]
gtkagg: no [skipping due to configuration]
tkagg: yes [installing; run-time loading from Python Tcl /
Tk]
wxagg: no [skipping due to configuration]
gtk: no [skipping due to configuration]
agg: yes [installing]
cairo: no [skipping due to configuration]
windowing: no [skipping due to configuration]
Workaround:
Explicitly specify matplotlib.use("Agg") in code.
Root Cause?
In file setupext.py, the subclass BackendTkAgg overrides the check() method. This means tkagg never checks the configuration file (this behaviour is normally inherited from the original check()). Note the other GUI backend classes implement the check_requirements() method.
class BackendTkAgg(OptionalBackendPackage):
name = "tkagg"
force = True
def check(self):
return "installing; run-time loading from Python Tcl / Tk"Is this a bug or is tkagg a required dependency?