add pt2tf tool

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

@@ -0,0 +1,39 @@
+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
+
+
+@onnx_op("Flatten")
+@tf_func(tf.layers.flatten)
+class Flatten(BackendHandler):
+
+  @classmethod
+  def _common(cls, node, **kwargs):
+    x = kwargs["tensor_dict"][node.inputs[0]]
+    shape = tf.shape(x)
+    x_rank = len(x.shape)
+    axis = node.attrs.get("axis", 1)
+
+    if axis == 1 and x_rank > 1:
+      return [cls.make_tensor_from_onnx_node(node, **kwargs)]
+
+    if axis == 0:
+      cal_shape = (1, -1)
+    else:
+      cal_shape = (tf.reduce_prod(shape[0:axis]),
+                   tf.reduce_prod(shape[axis:tf.size(shape)]))
+    return [tf.reshape(x, cal_shape)]
+
+  @classmethod
+  def version_1(cls, node, **kwargs):
+    return cls._common(node, **kwargs)
+
+  @classmethod
+  def version_9(cls, node, **kwargs):
+    return cls._common(node, **kwargs)
+
+  @classmethod
+  def version_11(cls, node, **kwargs):
+    return cls._common(node, **kwargs)