fix generate_proposals (#23797)

* test=develop fix generate_proposals

python/paddle/fluid/layers/detection.py

@@ -2746,7 +2746,8 @@ def generate_proposals(scores,
                        nms_thresh=0.5,
                        min_size=0.1,
                        eta=1.0,
-                       name=None):
+                       name=None,
+                       return_rois_num=False):
     """
     **Generate proposal Faster-RCNN**
 
@@ -2793,7 +2794,10 @@ def generate_proposals(scores,
             width < min_size. The data type must be float32. `0.1` by default.
         eta(float): Apply in adaptive NMS, if adaptive `threshold > 0.5`,
             `adaptive_threshold = adaptive_threshold * eta` in each iteration.
-
+        return_rois_num(bool): When setting True, it will return a 1D Tensor with shape [N, ] that includes Rois's 
+            num of each image in one batch. The N is the image's num. For example, the tensor has values [4,5] that represents
+            the first image has 4 Rois, the second image has 5 Rois. It only used in rcnn model. 
+            'False' by default. 
     Returns:
         tuple:
         A tuple with format ``(rpn_rois, rpn_roi_probs)``.
@@ -2847,7 +2851,10 @@ def generate_proposals(scores,
     rpn_roi_probs.stop_gradient = True
     rpn_rois_lod.stop_gradient = True
 
+    if return_rois_num:
         return rpn_rois, rpn_roi_probs, rpn_rois_lod
+    else:
+        return rpn_rois, rpn_roi_probs
 
 
 def box_clip(input, im_info, name=None):

python/paddle/fluid/tests/test_detection.py

@@ -505,7 +505,7 @@ class TestGenerateProposals(unittest.TestCase):
                 name='bbox_deltas',
                 shape=[num_anchors * 4, 8, 8],
                 dtype='float32')
-            rpn_rois, rpn_roi_probs, _ = fluid.layers.generate_proposals(
+            rpn_rois, rpn_roi_probs = fluid.layers.generate_proposals(
                 name='generate_proposals',
                 scores=scores,
                 bbox_deltas=bbox_deltas,

python/paddle/fluid/tests/unittests/test_generate_proposals_op.py

@@ -282,8 +282,6 @@ class TestGenerateProposalsOp(OpTest):
         self.outputs = {
             'RpnRois': (self.rpn_rois[0], [self.lod]),
             'RpnRoiProbs': (self.rpn_roi_probs[0], [self.lod]),
-            'RpnRoisLod': (np.asarray(
-                self.lod, dtype=np.int32))
         }
 
     def test_check_output(self):
@@ -328,5 +326,35 @@ class TestGenerateProposalsOp(OpTest):
             self.nms_thresh, self.min_size, self.eta)
 
 
+class TestGenerateProposalsOutLodOp(TestGenerateProposalsOp):
+    def set_data(self):
+        self.init_test_params()
+        self.init_test_input()
+        self.init_test_output()
+        self.inputs = {
+            'Scores': self.scores,
+            'BboxDeltas': self.bbox_deltas,
+            'ImInfo': self.im_info.astype(np.float32),
+            'Anchors': self.anchors,
+            'Variances': self.variances
+        }
+
+        self.attrs = {
+            'pre_nms_topN': self.pre_nms_topN,
+            'post_nms_topN': self.post_nms_topN,
+            'nms_thresh': self.nms_thresh,
+            'min_size': self.min_size,
+            'eta': self.eta,
+            'return_rois_num': True
+        }
+
+        self.outputs = {
+            'RpnRois': (self.rpn_rois[0], [self.lod]),
+            'RpnRoiProbs': (self.rpn_roi_probs[0], [self.lod]),
+            'RpnRoisLod': (np.asarray(
+                self.lod, dtype=np.int32))
+        }
+
+
 if __name__ == '__main__':
     unittest.main()