add pt2tf tool

pt2tf/onnx-tensorflow/onnx_tf/handlers/backend/sum.py

@@ -0,0 +1,33 @@
+import tensorflow as tf
+
+from onnx_tf.handlers.backend_handler import BackendHandler
+from onnx_tf.handlers.handler import onnx_op
+from onnx_tf.handlers.handler import tf_func
+from .math_mixin import ArithmeticMixin
+
+
+@onnx_op("Sum")
+@tf_func(tf.add_n)
+class Sum(ArithmeticMixin, BackendHandler):
+
+  @classmethod
+  def _common(cls, node, **kwargs):
+    tensor_dict = kwargs["tensor_dict"]
+    return [
+        cls.make_tensor_from_onnx_node(
+            node,
+            inputs=[[tensor_dict.get(inp, None) for inp in node.inputs]],
+            **kwargs)
+    ]
+
+  @classmethod
+  def version_1(cls, node, **kwargs):
+    return cls._common(node, **kwargs)
+
+  @classmethod
+  def version_6(cls, node, **kwargs):
+    return cls._common(node, **kwargs)
+
+  @classmethod
+  def version_8(cls, node, **kwargs):
+    return cls._common(node, **kwargs)