From 4661f5589dc95a3bd3736848b820990c4c6e32d3 Mon Sep 17 00:00:00 2001
From: tangwei12 <tangwei12@baidu.com>
Date: Wed, 15 Aug 2018 16:01:53 +0800
Subject: [PATCH] random optimize

---
 paddle/fluid/operators/sampling_id_op.cc | 44 +++++++++++++++---------
 1 file changed, 27 insertions(+), 17 deletions(-)

diff --git a/paddle/fluid/operators/sampling_id_op.cc b/paddle/fluid/operators/sampling_id_op.cc
index 4929a7edc2..f8f94553be 100644
--- a/paddle/fluid/operators/sampling_id_op.cc
+++ b/paddle/fluid/operators/sampling_id_op.cc
@@ -36,9 +36,19 @@ class SamplingIdKernel : public framework::OpKernel<T> {
     std::vector<T> ins_vector;
     framework::TensorToVector(*input, context.device_context(), &ins_vector);
 
+    unsigned int seed = static_cast<unsigned int>(ctx.Attr<int>("seed"));
+    std::minstd_rand engine;
+    if (seed == 0) {
+      seed = std::random_device()();
+    }
+    engine.seed(seed);
+    std::uniform_real_distribution<T> dist(
+        static_cast<T>(ctx.Attr<float>("min")),
+        static_cast<T>(ctx.Attr<float>("max")));
+
     std::vector<T> ids(batch_size);
     for (size_t i = 0; i < batch_size; ++i) {
-      double r = getRandReal();
+      double r = dist(engine);
       int idx = width - 1;
       for (int j = 0; j < width; ++j) {
         if ((r -= ins_vector[i * width + j]) < 0) {
@@ -57,16 +67,6 @@ class SamplingIdKernel : public framework::OpKernel<T> {
     output->mutable_data<T>(context.GetPlace());
     framework::TensorFromVector(ids, context.device_context(), output);
   }
-
- private:
-  double getRandReal() const {
-    std::random_device
-        rd;  // Will be used to obtain a seed for the random number engine
-    std::mt19937 gen(rd());  // Standard mersenne_twister_engine seeded with
-                             // rd()
-    std::uniform_real_distribution<> dis(1.0, 2.0);
-    return dis(gen);
-  }
 };
 
 class SamplingIdOp : public framework::OperatorWithKernel {
@@ -78,6 +78,9 @@ class SamplingIdOp : public framework::OperatorWithKernel {
                    "Input(X) of SamplingIdOp should not be null.");
     PADDLE_ENFORCE(ctx->HasOutput("Out"),
                    "Output(Out) of SamplingIdOp should not be null.");
+    PADDLE_ENFORCE(
+        ctx->Attrs().Get<float>("min") < ctx->Attrs().Get<float>("max"),
+        "min must less then max");
 
     auto input_dims = ctx->GetInputDim("X");
     PADDLE_ENFORCE(input_dims.size() == 2,
@@ -99,7 +102,17 @@ class SamplingIdOpMaker : public framework::OpProtoAndCheckerMaker {
     AddComment(R"DOC(
 SamplingId Operator.
 A layer for sampling id from multinomial distribution from the
- input layer. Sampling one id for one sample.)DOC");
+ input. Sampling one id for one sample.)DOC");
+    AddAttr<float>("min", "Minimum value of random. [default 0.0].")
+        .SetDefault(0.0f);
+    AddAttr<float>("max", "Maximun value of random. [default 1.0].")
+        .SetDefault(1.0f);
+    AddAttr<int>("seed",
+                 "Random seed used for the random number engine. "
+                 "0 means use a seed generated by the system."
+                 "Note that if seed is not 0, this operator will always "
+                 "generate the same random numbers every time. [default 0].")
+        .SetDefault(0);
   }
 };
 }  // namespace operators
@@ -109,8 +122,5 @@ namespace ops = paddle::operators;
 REGISTER_OPERATOR(sampling_id, ops::SamplingIdOp, ops::SamplingIdOpMaker,
                   paddle::framework::EmptyGradOpMaker);
 
-REGISTER_OP_CPU_KERNEL(
-    sampling_id, ops::SamplingIdKernel<paddle::platform::CPUDeviceContext, int>,
-    ops::SamplingIdKernel<paddle::platform::CPUDeviceContext, int64_t>,
-    ops::SamplingIdKernel<paddle::platform::CPUDeviceContext, float>,
-    ops::SamplingIdKernel<paddle::platform::CPUDeviceContext, double>);
+REGISTER_OP_CPU_KERNEL(sampling_id, paddle::operators::SamplingIdKernel<float>,
+                       paddle::operators::SamplingIdKernel<double>);
-- 
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