Precision-Recall Curve: switch axes in plot

[mykappa]

🚀 Feature

In the precision-recall curve plot, place recall on the x-axis and precision on the y-axis.

Motivation

In my experience, precision-recall curves with precision on the y-axis (ordinate) and recall on the x-axis (abscissa) are much more common than the other way around (i.e., how the plot is generated at the moment). A quick Google image search confirms this. And it is also the case in the sklearn implementation.

Pitch

Place recall on the x-axis and precision on the y-axis in PrecisionRecallCurve.plot()

Alternatives

Add an option to choose between both variants.

Additional context

Furthermore, an option for plotting the chance value similar to sklearn's plot_chance_level argument would be a welcome addition to the precision-recall curve plot.

[Yann-CV]

@SkafteNicki for info this linked to #2200