From 7c42aad412e634c7e8853d170c3f516fc3e6b2bf Mon Sep 17 00:00:00 2001
From: Yu Yang <yuyang18@baidu.com>
Date: Wed, 2 Aug 2017 16:07:51 +0800
Subject: [PATCH] Initialize Gradient Checker

Add get_numeric_gradient API and its unittest.
---
 paddle/pybind/pybind.cc                       | 10 ++-
 .../paddle/v2/framework/tests/CMakeLists.txt  |  3 +-
 .../v2/framework/tests/gradient_checker.py    | 69 +++++++++++++++++++
 3 files changed, 79 insertions(+), 3 deletions(-)
 create mode 100644 python/paddle/v2/framework/tests/gradient_checker.py

diff --git a/paddle/pybind/pybind.cc b/paddle/pybind/pybind.cc
index ee5f675e25..e79ad49b6d 100644
--- a/paddle/pybind/pybind.cc
+++ b/paddle/pybind/pybind.cc
@@ -77,8 +77,14 @@ PYBIND11_PLUGIN(core) {
            })
       .def("set", paddle::pybind::PyTensorSetFromArray<float>)
       .def("set", paddle::pybind::PyTensorSetFromArray<int>)
-      .def("shape",
-           [](pd::Tensor& self) { return pd::vectorize(self.dims()); });
+      .def("shape", [](pd::Tensor& self) { return pd::vectorize(self.dims()); })
+      .def("set_float_element",
+           [](pd::Tensor& self, size_t offset, float f) {
+             self.data<float>()[offset] = f;
+           })
+      .def("get_float_element", [](pd::Tensor& self, size_t offset) -> float {
+        return self.data<float>()[offset];
+      });
 
   py::class_<pd::Variable>(m, "Variable", R"DOC(Variable Class.
 
diff --git a/python/paddle/v2/framework/tests/CMakeLists.txt b/python/paddle/v2/framework/tests/CMakeLists.txt
index cdaaa60674..494c517a9b 100644
--- a/python/paddle/v2/framework/tests/CMakeLists.txt
+++ b/python/paddle/v2/framework/tests/CMakeLists.txt
@@ -13,4 +13,5 @@ add_python_test(test_framework
     test_sigmoid_op.py
     test_softmax_op.py
     test_rowwise_add_op.py
-    test_network.py)
+    test_network.py
+    gradient_checker.py)
diff --git a/python/paddle/v2/framework/tests/gradient_checker.py b/python/paddle/v2/framework/tests/gradient_checker.py
new file mode 100644
index 0000000000..d7e5de8252
--- /dev/null
+++ b/python/paddle/v2/framework/tests/gradient_checker.py
@@ -0,0 +1,69 @@
+import paddle.v2.framework.core as core
+from paddle.v2.framework.create_op_creation_methods import op_creations
+import numpy
+import unittest
+
+
+def get_numeric_gradient(op,
+                         input_values,
+                         output_name,
+                         input_to_check,
+                         delta=1e-5,
+                         local_scope=None):
+    if local_scope is None:
+        local_scope = core.Scope()
+    for var_name in input_values:
+        var = local_scope.new_var(var_name)
+        tensor = var.get_tensor()
+        tensor.set_dims(input_values[var_name].shape)
+        tensor.alloc_float()
+        tensor.set(input_values[var_name])
+
+    for output in op.outputs():
+        local_scope.new_var(output).get_tensor()
+
+    op.infer_shape(local_scope)
+
+    for output in op.outputs():
+        local_scope.find_var(output).get_tensor().alloc_float()
+
+    cpu_ctx = core.DeviceContext.cpu_context()
+
+    def get_output():
+        op.run(local_scope, cpu_ctx)
+        return numpy.array(local_scope.find_var(output_name).get_tensor()).sum()
+
+    def product(dim):
+        return reduce(lambda a, b: a * b, dim, 1)
+
+    tensor_to_check = local_scope.find_var(input_to_check).get_tensor()
+    tensor_size = product(tensor_to_check.get_dims())
+    gradient_flat = numpy.zeros(shape=(tensor_size, ), dtype='float32')
+    for i in xrange(tensor_size):
+        origin = tensor_to_check.get_float_element(i)
+        x_pos = origin + delta
+        tensor_to_check.set_float_element(i, x_pos)
+        y_pos = get_output()
+
+        x_neg = origin - delta
+        tensor_to_check.set_float_element(i, x_neg)
+        y_neg = get_output()
+
+        tensor_to_check.set_float_element(i, origin)  # restore old value
+        gradient_flat[i] = (y_pos - y_neg) / delta / 2
+    return gradient_flat.reshape(tensor_to_check.get_dims())
+
+
+if __name__ == '__main__':
+
+    class GetNumericGradientTest(unittest.TestCase):
+        def test_add_op(self):
+            add_op = op_creations.add_two(X="X", Y="Y", Out="Z")
+            x = numpy.random.random((10, 1)).astype("float32")
+            y = numpy.random.random((10, 1)).astype("float32")
+
+            arr = get_numeric_gradient(add_op, {'X': x, "Y": y}, 'Z', 'X')
+
+            self.assertAlmostEqual(arr.mean(), 1.0, delta=1e-2)
+
+    unittest.main()
-- 
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