Merge pull request #4837 from QiJune/pybind_feed_fetch_method

export feed/fetch variable method to Python

paddle/framework/feed_fetch_method.h

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License. */
+
+#pragma once
+#include "paddle/framework/scope.h"
+#include "paddle/framework/variable.h"
+
+namespace paddle {
+namespace framework {
+
+template <typename T>
+void SetFeedVariable(const LoDTensor& input, const std::string& var_name,
+                     size_t index) {
+  // If var_name Variable is not found in GlobalScope, a new variable will
+  // be created.
+  Variable* g_feed_value = GetGlobalScope().Var(var_name);
+  auto& feed_inputs =
+      *(g_feed_value->GetMutable<std::vector<paddle::framework::LoDTensor>>());
+  if (index >= feed_inputs.size()) {
+    feed_inputs.resize(index + 1);
+  }
+  // shared data with input tensor
+  feed_inputs[index].ShareDataWith<T>(input);
+  // set lod
+  feed_inputs[index].set_lod(input.lod());
+}
+
+LoDTensor& GetFetchVariable(const std::string& var_name, size_t index) {
+  // Since we want to fetch LodTensor from a variable, the variable must
+  // be created alreadly.
+  Variable* g_fetch_value = GetGlobalScope().FindVar(var_name);
+  auto& fetch_outputs =
+      *(g_fetch_value->GetMutable<std::vector<paddle::framework::LoDTensor>>());
+  PADDLE_ENFORCE_LT(index, fetch_outputs.size());
+  return fetch_outputs[index];
+}
+
+}  // namespace framework
+}  // namespace paddle

paddle/pybind/pybind.cc

@@ -16,6 +16,7 @@ limitations under the License. */
 
 #include "paddle/framework/backward.h"
 #include "paddle/framework/executor.h"
+#include "paddle/framework/feed_fetch_method.h"
 #include "paddle/framework/lod_tensor.h"
 #include "paddle/framework/tensor_array.h"
 #include "paddle/operators/cond_op.h"
@@ -403,6 +404,10 @@ All parameter, weight, gradient are variables in Paddle.
   m.def("unique_integer", UniqueIntegerGenerator);
 
   m.def("is_compile_gpu", IsCompileGPU);
+  m.def("set_feed_variable_float", framework::SetFeedVariable<float>);
+  m.def("set_feed_variable_double", framework::SetFeedVariable<double>);
+  m.def("set_feed_variable_int", framework::SetFeedVariable<int>);
+  m.def("get_fetch_variable", framework::GetFetchVariable);
 
   BindProgramDesc(m);
   BindBlockDesc(m);

python/paddle/v2/framework/tests/test_feed_fetch_method.py

+import paddle.v2.framework.core as core
+import unittest
+import numpy as np
+
+
+class TestFeedFetch(unittest.TestCase):
+    def test_feed_fetch(self):
+        place = core.CPUPlace()
+        input_array = np.ones((4, 4, 6)).astype("float32")
+        input_array[0, 0, 0] = 3
+        input_array[3, 3, 5] = 10
+        input_tensor = core.LoDTensor([[0, 2, 4]])
+        input_tensor.set(input_array, place)
+
+        core.set_feed_variable_float(input_tensor, "feed", 0)
+
+        output_tensor = core.get_fetch_variable("feed", 0)
+
+        output_lod = output_tensor.lod()
+        self.assertEqual(0, output_lod[0][0])
+        self.assertEqual(2, output_lod[0][1])
+        self.assertEqual(4, output_lod[0][2])
+
+        output_array = np.array(output_tensor)
+        self.assertEqual(3, output_array[0, 0, 0])
+        self.assertEqual(10, output_array[3, 3, 5])
+
+
+if __name__ == "__main__":
+    unittest.main()