add pt2tf tool

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

@@ -0,0 +1,29 @@
+import copy
+
+import tensorflow as tf
+import numpy as np
+
+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("LRN")
+@tf_func(tf.nn.lrn)
+class LRN(BackendHandler):
+
+  @classmethod
+  def version_1(cls, node, **kwargs):
+    attrs = copy.deepcopy(node.attrs)
+    alpha = attrs.get("alpha", 1e-4)
+    attrs.setdefault("beta", 0.75)
+    size = attrs["size"]
+    attrs["alpha"] = alpha / size
+    attrs["depth_radius"] = np.floor([(size - 1) / 2.])[0]
+    # TODO: LRN in tf accepts radius
+    # but in ONNX/Caffe accepts diameter.
+    # This could be a problem.
+    return [
+        cls.make_tensor_from_onnx_node(
+            node, attrs=attrs, c_last_only=True, **kwargs)
+    ]