Improvements to PrecisionRecallCurve

[bbengfort]

There are a few things that can be updated in the PrecisionRecallCurve visualizer:

• [x] allow the user to specify colors as a list of colors or a colormap and use resolve_colors in _draw_multiclass.
• [ ] refactor shared _get_y_scores as a mixin, utility function, or shared base class for ROCAUC and PrecisionRecallCurve.
• [x] Allow user to customize the values of the iso_f1_curves (hard coded to [0.2,0.4,.06,0.8] now).
• [x] Allow user to input training and testing set instead of using train_test_split in the quick method.
• [x] Remove grid in multiclass case so it's not as busy

See also #602

[sahilbansal17]

I would like to work on it.

[rebeccabilbro]

That would be great @sahilbansal17! Here's our guide to contributing, and let us know if there's anything we can do to help!

[sahilbansal17]

Thank you for the quick response.

[rohit-ganapathy]

Hello! I'm extremely interested in working on this. Let me know if i can!

[bbengfort]

@rohit-ganapathy It would be great if you could help out on this. Check out our contributor's guide and feel free to open a PR right after you get started.

[bbengfort]

Thank you @rohit-ganapathy for taking care of two of these items!