Update PR curve (#1428)

* Update PR curve

* legend outside

* list(Path().glob())

test.py

@@ -213,7 +213,7 @@ def test(data,
     # Compute statistics
     stats = [np.concatenate(x, 0) for x in zip(*stats)]  # to numpy
     if len(stats) and stats[0].any():
-        p, r, ap, f1, ap_class = ap_per_class(*stats, plot=plots, fname=save_dir / 'precision-recall_curve.png')
+        p, r, ap, f1, ap_class = ap_per_class(*stats, plot=plots, save_dir=save_dir, names=names)
         p, r, ap50, ap = p[:, 0], r[:, 0], ap[:, 0], ap.mean(1)  # [P, R, AP@0.5, AP@0.5:0.95]
         mp, mr, map50, map = p.mean(), r.mean(), ap50.mean(), ap.mean()
         nt = np.bincount(stats[3].astype(np.int64), minlength=nc)  # number of targets per class