PPSD: Need to adjust to set_clim API change in matplotlib 3.1-3.3

[megies]

We need to adjust some PPSD plotting internals to a matplotlib API change:

[...]\obspy\signal\spectral_estimation.py:2096: MatplotlibDeprecationWarning: 
The set_clim function was deprecated in Matplotlib 3.1 and will be removed in 3.3. Use ScalarMappable.set_clim instead.
  cb.set_clim(*fig.ppsd.color_limits)

@millipedes this is something pretty simple and confined, if you wanna give it a shot? It might need an if/else depending on matplotlib version, but actually my guess is that the mentioned ScalarMappable.set_clim should be in all old matplotlibs as well, but needs to be checked. This should be worked on branching off of maintenance_1.2.x

[megies]

1.2.x is still very lax about matplotlib version, so we should make sure the to-be-changed matplotlib calls work on old versions:

obspy/setup.py

Line 113 in 2926827

'matplotlib>=1.1.0',

[krischer]

Do you want to do this for 1.2.2? Might be a good idea but also not super urgent.

[megies]

Ideally yes, since we never know if anything upcoming will ever warrant a 1.2.3

[millipedes]

@megies I will start to take a look and post any questions I may have. Thank you. I have also been looking into issue #2605 and will likely be posting some questions/comments there a little later today.

[millipedes]

@megies, here is my understanding of the issue, please let me know if I have erred (branching off of maintenance_1.2.x):

1. First determine if ScalarMappable.set_clim is in older versions of matplotlib
2. if so then change obspy/signal/spectral_estimation.py to use it
3. if not then make an if/else statement that would either have the user using set_clim or ScalarMappable.set_clim depending on version.

I am a little confused on the matplotlib version. At the moment I see that the current master branch has 'matplotlib>=3.2.0', but I believe that we are looking to support older versions of obspy? If so, how can I access older versions?

CC
@dsentinel

[megies]

@millipedes yes, thats exactly what is to do here.

At the moment I see that the current master branch has 'matplotlib>=3.2.0'

The master branch is the base for an upcoming obspy 2.0 release with massive changes, like dropping Python 2 support and all the compatibility gymnastics we been doing for that. we also bumped dependency versions massively.

The maintenance_... branches are for pure bug fix / point releases, not changing any features of the base version.

You can also have a look at this: https://github.com/obspy/obspy/wiki#developer-corner
Ans specifically the branching model: https://github.com/obspy/obspy/wiki/ObsPy-Git-Branching-Model

.., but I believe that we are looking to support older versions of obspy? If so, how can I access older versions?

This will be a fix on the maintenance_1.2.x branch, so the older dependency version still hold there.

In any case @millipedes, things have changed a bit with all the reports of installation problems with newest numpy, so we'll want to do the release ASAP, so I'll handle this one myself I think, to avoid potential back and forth communication. I'll ping you in other issues again, that don't have such a strong time constraint. :-)

[megies]

Should be OK like this, let's see what CI has to say

[megies]

Looks OK on those Travis builds that can still run. I think all the older ones (2.7 etc) are already switched off on Travis and Appveyor