Need to set matplotlib backend for remote plotting?

[rjleveque]

PR #120 removed statements setting the backend to Agg if it's not already set.

Does this break plotting on remote machines where the backend is set by default to something that requires $DISPLAY to be set? I think it might, but need to investigate...

Should we add an attribute to ClawPlotData to allow the user to specify this directly in setplot.py, e.g.

   plotdata.mpl_backend = 'Agg'

[mandli]

I guess this would be a problem if the default is "tk agg" for instance and it was a remote machine. There are already ways for the backend to be set by default in matplotlib, I am not sure that we should override that behavior. Maybe we could detect if the DISPLAY variable is set properly and default to agg otherwise?

[cjvogl]

Actually just had this issue using the HYAK cluster at UW... so it does come up now and then.

[mandli]

@cjvogl Do you have a workaround we could use in these cases?

[cjvogl]

@mandli I added import matplotlib followed by matplotlib.use('Agg') to the very top of any plotting scripts. Not the most elegant solution, but it seems to have worked.

[mandli]

That is The recomended way to override the default backend actually. You can also set the default in a .matplotlibrc file on that machine (melt recommendation). I feel for advanced users running on headless machines that these types of work around are fairly painless where as a novice user might run into troubles if we override their default backend.

[ketch]

I guess we can just add this workaround to the documentation and close this issue.

[mandli]

Added issue clawpack/doc#205 to address this.