modify @ to be compatible to python2

ppdet/data/transform/op_helper.py

@@ -482,7 +482,7 @@ def transform_bbox(bbox,
     n = len(bbox)
     xy = np.ones((n * 4, 3), dtype=np.float32)
     xy[:, :2] = bbox[:, [0, 1, 2, 3, 0, 3, 2, 1]].reshape(n * 4, 2)
-    xy = xy @ M.T
+    xy = np.matmul(xy, M.T)
     if perspective:
         xy = (xy[:, :2] / xy[:, 2:3]).reshape(n, 8)
     else:

ppdet/data/transform/operators.py

@@ -2919,7 +2919,10 @@ class RandomPerspective(BaseOperator):
         T[1, 2] = random.uniform(0.5 - self.translate, 0.5 + self.translate) * height
 
         # matmul
-        M = T @ S @ R @ P @ C
+        # M = T @ S @ R @ P @ C
+        M = np.eye(3)
+        for cM in [T, S, R, P, C]:
+            M = np.matmul(M, cM)
         if (self.border[0] != 0) or (self.border[1] != 0) or (M != np.eye(3)).any():
             if self.perspective:
                 im = cv2.warpPerspective(im, M, dsize=(width, height), borderValue=self.border_value)