code release

xlib/math/nms.py

@@ -0,0 +1,30 @@
+import numpy as np
+
+def nms(x1, y1, x2, y2, scores, thresh):
+    """
+    Non-Maximum Suppression
+
+        x1,y1,x2,y2,scores  np.ndarray of box coords with the same length
+
+    returns indexes of boxes
+    """
+    keep = []
+    if len(x1) == 0:
+        return keep
+
+    areas = (x2 - x1 + 1) * (y2 - y1 + 1)
+    order = scores.argsort()[::-1]
+
+    keep = []
+    while order.size > 0:
+        i = order[0]
+        keep.append(i)
+        xx_1, yy_1 = np.maximum(x1[i], x1[order[1:]]), np.maximum(y1[i], y1[order[1:]])
+        xx_2, yy_2 = np.minimum(x2[i], x2[order[1:]]), np.minimum(y2[i], y2[order[1:]])
+
+        width, height = np.maximum(0.0, xx_2 - xx_1 + 1), np.maximum(0.0, yy_2 - yy_1 + 1)
+        ovr = width * height / (areas[i] + areas[order[1:]] - width * height)
+
+        inds = np.where(ovr <= thresh)[0]
+        order = order[inds + 1]
+    return keep