Visualization / integrate savvy package

[jdherman]

Currently we have limited plotting features:
https://github.com/SALib/SALib/tree/master/src/SALib/plotting

I used to be concerned about adding dependencies, but I think it could be valuable to have more plotting functions inside the library as we think about v2.0. Especially for standard plot styles used for sensitivity indices.

Two (maybe more) ideas here:

1. Because indices can now be stored as pandas dataframes, we can extend pandas plotting functions. An example is the bar plot created by @ConnectedSystems
   https://github.com/SALib/SALib/blob/master/src/SALib/plotting/bar.py

where the usage is Si_df.plot(kind='...' ...).
(this might coincide with making dataframes the default return type)

2. The coolest SA visualizations I've seen are in savvy:
   https://github.com/houghb/savvy

It looks like this hasn't been updated in a while. I wonder if we could absorb some of the plot styles into the SALib.plotting module, if it's ok with @houghb .

The potential downside would be adding dependencies to some of the network plotting libraries, which in my experience have some issues with cross-platform compatibility. Maybe these could be optional to avoid breaking the installation.

Ideally the plots can apply to as many of the SA methods as possible. In general I don't see a reason to restrict this if there's interest.

[houghb]

You're welcome to copy any of the plot styles and code from savvy that you'd like @jdherman, as you said I haven't updated that in a long time and don't have time to do so now (it is probably several major versions of all packages behind). Those visualizations were very helpful for me and I hope they can be repurposed to help others!

[willu47]

@houghb - if you're not actively maintaining savvy any more, perhaps you could consider transferring the repository to the SALib organisation - we could then gradually migrate your visualisation code into SALib, or keep savvy as a sub-package of the SALib library? Then you'd effectively become an SALib author!

I'd prefer not to manually copy (duplicate) code where possible, rather to import the functionality from the savvy library into SALib.

There are various options of course - more or less disruptive, but it would be nice to have the SALib family of tools together in one place.