text: Title: Precision Recall Curve
  Body: **Describe the solution you'd like**
  For imbalanced classification problems it would be wonderful to have a precision recall plot. This would make a nice companion to ROC/AUC plots.
  
  http://scikit-learn.org/stable/auto_examples/model_selection/plot_precision_recall.html#sphx-glr-auto-examples-model-selection-plot-precision-recall-py