Add `matrix_nms` op (#645)

* Add `matrix_nms` op

* Make OP registration more robust

ppdet/core/workspace.py

@@ -140,8 +140,22 @@ def get_registered_modules():
 
 
 def make_partial(cls):
-    op_module = importlib.import_module(cls.__op__.__module__)
-    op = getattr(op_module, cls.__op__.__name__)
+    if isinstance(cls.__op__, str):
+        sep = cls.__op__.split('.')
+        op_name = sep[-1]
+        op_module = importlib.import_module('.'.join(sep[:-1]))
+    else:
+        op_name = cls.__op__.__name__
+        op_module = importlib.import_module(cls.__op__.__module__)
+
+    if not hasattr(op_module, op_name):
+        import logging
+        logger = logging.getLogger(__name__)
+        logger.warn('{} OP not found, maybe a newer version of paddle '
+                    'is required.'.format(cls.__op__))
+        return cls
+
+    op = getattr(op_module, op_name)
     cls.__category__ = getattr(cls, '__category__', None) or 'op'
 
     def partial_apply(self, *args, **kwargs):

ppdet/modeling/ops.py

@@ -30,7 +30,7 @@ __all__ = [
     'GenerateProposals', 'MultiClassNMS', 'BBoxAssigner', 'MaskAssigner',
     'RoIAlign', 'RoIPool', 'MultiBoxHead', 'SSDLiteMultiBoxHead',
     'SSDOutputDecoder', 'RetinaTargetAssign', 'RetinaOutputDecoder', 'ConvNorm',
-    'DeformConvNorm', 'MultiClassSoftNMS', 'LibraBBoxAssigner'
+    'DeformConvNorm', 'MultiClassSoftNMS', 'MatrixNMS', 'LibraBBoxAssigner'
 ]
 
 
@@ -492,6 +492,32 @@ class MultiClassNMS(object):
         self.background_label = background_label
 
 
+@register
+@serializable
+class MatrixNMS(object):
+    __op__ = 'paddle.fluid.layers.matrix_nms'
+    __append_doc__ = True
+
+    def __init__(self,
+                 score_threshold=.05,
+                 post_threshold=.05,
+                 nms_top_k=-1,
+                 keep_top_k=100,
+                 use_gaussian=False,
+                 gaussian_sigma=2.,
+                 normalized=False,
+                 background_label=0):
+        super(MultiClassNMS, self).__init__()
+        self.score_threshold = score_threshold
+        self.post_threshold = post_threshold
+        self.nms_top_k = nms_top_k
+        self.keep_top_k = keep_top_k
+        self.normalized = normalized
+        self.use_gaussian = use_gaussian
+        self.gaussian_sigma = gaussian_sigma
+        self.background_label = background_label
+
+
 @register
 @serializable
 class MultiClassSoftNMS(object):