separate index tensor from candidate tensors in multiplex_op

doc/faq/index_cn.rst

@@ -391,3 +391,124 @@ PaddlePaddle保存的模型参数文件内容由16字节头信息和网络参数
 * 如果发现最早的报错就是网络通信的问题，很有可能是非独占方式执行导致的端口冲突，可以联系OP，看当前MPI集群是否支持resource=full参数提交，如果支持增加此参数提交，并更换job 端口。
 
 * 如果当前MPI集群并不支持任务独占模式，可以联系OP是否可以更换集群或升级当前集群。
+
+19. PaddlePaddle如何输出多个层
+------------------------------
+
+* 将需要输出的层作为 :code:`paddle.inference.Inference()` 接口的 :code:`output_layer` 参数输入，代码如下：
+
+..  code-block:: python
+
+    inferer = paddle.inference.Inference(output_layer=[layer1, layer2], parameters=parameters)
+
+* 指定要输出的字段进行输出。以输出 :code:`value` 字段为例，代码如下：
+
+..  code-block:: python
+
+    out = inferer.infer(input=data_batch, flatten_result=False, field=["value"])
+
+这里设置 :code:`flatten_result=False`，得到的输出结果是元素个数等于输出字段数的 :code:`list`，该 :code:`list` 的每个元素是由所有输出层相应字段结果组成的 :code:`list`，每个字段结果的类型是 :code:`numpy.array`。:code:`flatten_result` 的默认值为 :code:`True`，该情况下，PaddlePaddle会分别对每个字段将所有输出层的结果按行进行拼接，如果各输出层该字段 :code:`numpy.array` 结果的相应维数不匹配，程序将不能正常运行。
+
+20. :code:`paddle.layer.memory` 的参数 :code:`name` 如何使用
+-------------------------------------------------------------
+
+* :code:`paddle.layer.memory` 用于获取特定layer上一时间步的输出，该layer是通过参数 :code:`name` 指定，即，:code:`paddle.layer.memory` 会关联参数 :code:`name` 取值相同的layer，并将该layer上一时间步的输出作为自身当前时间步的输出。
+
+* PaddlePaddle的所有layer都有唯一的name，用户通过参数 :code:`name` 设定，当用户没有显式设定时，PaddlePaddle会自动设定。而 :code:`paddle.layer.memory` 不是真正的layer，其name由参数 :code:`memory_name` 设定，当用户没有显式设定时，PaddlePaddle会自动设定。:code:`paddle.layer.memory` 的参数 :code:`name` 用于指定其要关联的layer，需要用户显式设定。
+
+21. dropout 使用
+-----------------
+
+* 在PaddlePaddle中使用dropout有两种方式
+
+  * 在相应layer的 :code:`layer_atter` 设置 :code:`drop_rate`，以 :code:`paddle.layer.fc` 为例，代码如下：
+
+  ..  code-block:: python
+
+      fc = paddle.layer.fc(input=input, layer_attr=paddle.attr.ExtraLayerAttribute(drop_rate=0.5))
+
+  * 使用 :code:`paddle.layer.dropout`，以 :code:`paddle.layer.fc` 为例，代码如下：
+
+  ..  code-block:: python
+
+      fc = paddle.layer.fc(input=input)
+      drop_fc = paddle.layer.dropout(input=fc, dropout_rate=0.5)
+
+* :code:`paddle.layer.dropout` 实际上使用了 :code:`paddle.layer.add_to`，并在该layer里采用第一种方式设置 :code:`drop_rate` 来使用dropout的。这种方式对内存消耗较大。
+
+* PaddlePaddle在激活函数里实现dropout，而不是在layer里实现。
+
+* :code:`paddle.layer.lstmemory`、:code:`paddle.layer.grumemory`、:code:`paddle.layer.recurrent` 不是通过一般的方式来实现对输出的激活，所以不能采用第一种方式在这几个layer里设置 :code:`drop_rate` 来使用dropout。若要对这几个layer使用dropout，可采用第二种方式，即使用 :code:`paddle.layer.dropout`。
+
+22. 如何设置学习率退火（learning rate annealing）
+------------------------------------------------
+
+在相应的优化算法里设置learning_rate_schedule及相关参数，以使用Adam算法为例，代码如下：
+
+..  code-block:: python
+
+    optimizer = paddle.optimizer.Adam(
+        learning_rate=1e-3,
+        learning_rate_decay_a=0.5,
+        learning_rate_decay_b=0.75,
+        learning_rate_schedule="poly",)
+
+PaddlePaddle目前支持8种learning_rate_schedule，这8种learning_rate_schedule及其对应学习率计算方式如下：
+
+* "constant"
+
+  lr = learning_rate
+
+* "poly"
+
+  lr = learning_rate * pow(1 + learning_rate_decay_a * num_samples_processed, -learning_rate_decay_b)
+
+  其中，num_samples_processed为已训练样本数，下同。
+
+* "caffe_poly"
+
+  lr = learning_rate * pow(1.0 - num_samples_processed / learning_rate_decay_a, learning_rate_decay_b)
+
+* "exp"
+
+  lr = learning_rate * pow(learning_rate_decay_a, num_samples_processed / learning_rate_decay_b)
+
+* "discexp"
+
+  lr = learning_rate * pow(learning_rate_decay_a, floor(num_samples_processed / learning_rate_decay_b))
+
+* "linear"
+
+  lr = max(learning_rate - learning_rate_decay_a * num_samples_processed, learning_rate_decay_b)
+
+* "manual"
+
+  这是一种按已训练样本数分段取值的学习率退火方法。使用该learning_rate_schedule时，用户通过参数 :code:`learning_rate_args` 设置学习率衰减因子分段函数，当前的学习率为所设置 :code:`learning_rate` 与当前的衰减因子的乘积。以使用Adam算法为例，代码如下：
+
+  ..  code-block:: python
+
+      optimizer = paddle.optimizer.Adam(
+          learning_rate=1e-3,
+          learning_rate_schedule="manual",
+          learning_rate_args="1000:1.0,2000:0.9,3000:0.8",)
+
+  在该示例中，当已训练样本数小于等于1000时，学习率为 :code:`1e-3 * 1.0`；当已训练样本数大于1000小于等于2000时，学习率为 :code:`1e-3 * 0.9`；当已训练样本数大于2000时，学习率为 :code:`1e-3 * 0.8`。
+
+* "pass_manual"
+
+  这是一种按已训练pass数分段取值的学习率退火方法。使用该learning_rate_schedule时，用户通过参数 :code:`learning_rate_args` 设置学习率衰减因子分段函数，当前的学习率为所设置 :code:`learning_rate` 与当前的衰减因子的乘积。以使用Adam算法为例，代码如下：
+
+  ..  code-block:: python
+
+      optimizer = paddle.optimizer.Adam(
+          learning_rate=1e-3,
+          learning_rate_schedule="manual",
+          learning_rate_args="1:1.0,2:0.9,3:0.8",) 
+
+  在该示例中，当已训练pass数小于等于1时，学习率为 :code:`1e-3 * 1.0`；当已训练pass数大于1小于等于2时，学习率为 :code:`1e-3 * 0.9`；当已训练pass数大于2时，学习率为 :code:`1e-3 * 0.8`。
+
+23. 出现 :code:`Duplicated layer name` 错误怎么办
+--------------------------------------------------
+
+出现该错误的原因一般是用户对不同layer的参数 :code:`name` 设置了相同的取值。遇到该错误时，先找出参数 :code:`name` 取值相同的layer，然后将这些layer的参数 :code:`name` 设置为不同的值。
+

paddle/operators/crop_op.h

@@ -38,10 +38,10 @@ class CropKernel : public framework::OpKernel {
     auto out_stride = framework::stride(out->dims());
     auto offsets = context.Attr<std::vector<int>>("offsets");
     PADDLE_ENFORCE_EQ(
-        x->dims().size(), offsets.size(),
+        x->dims().size(), static_cast<int64_t>(offsets.size()),
         "Offsets size should be equal to dimension size of input tensor.");
     int64_t offset = 0;
-    for (int i = 0; i < offsets.size(); ++i) {
+    for (size_t i = 0; i < offsets.size(); ++i) {
       offset += (x_stride[i] * offsets[i]);
     }
     StridedMemcpy<T>(context.device_context(), x_data + offset, x_stride,
@@ -57,7 +57,7 @@ void CropGradFunction(const framework::ExecutionContext& context) {
     d_x->mutable_data<T>(context.GetPlace());
     auto offsets = context.Attr<std::vector<int>>("offsets");
     Eigen::array<std::pair<int, int>, D> paddings;
-    for (int i = 0; i < D; ++i) {
+    for (size_t i = 0; i < D; ++i) {
       paddings[i].first = offsets[i];
       paddings[i].second = d_x->dims()[i] - d_out->dims()[i] - offsets[i];
     }

paddle/operators/math/math_function.cc

@@ -48,6 +48,32 @@ void gemm<platform::CPUPlace, double>(const platform::DeviceContext& context,
               beta, C, ldc);
 }
 
+template <>
+void gemm<platform::CPUPlace, float>(const platform::DeviceContext& context,
+                                     const bool transA, const bool transB,
+                                     const int M, const int N, const int K,
+                                     const float alpha, const float* A,
+                                     const int lda, const float* B,
+                                     const int ldb, const float beta, float* C,
+                                     const int ldc) {
+  cblas_sgemm(CblasRowMajor, transA == false ? CblasNoTrans : CblasTrans,
+              transB == false ? CblasNoTrans : CblasTrans, M, N, K, alpha, A,
+              lda, B, ldb, beta, C, ldc);
+}
+
+template <>
+void gemm<platform::CPUPlace, double>(const platform::DeviceContext& context,
+                                      const bool transA, const bool transB,
+                                      const int M, const int N, const int K,
+                                      const double alpha, const double* A,
+                                      const int lda, const double* B,
+                                      const int ldb, const double beta,
+                                      double* C, const int ldc) {
+  cblas_dgemm(CblasRowMajor, transA == false ? CblasNoTrans : CblasTrans,
+              transB == false ? CblasNoTrans : CblasTrans, M, N, K, alpha, A,
+              lda, B, ldb, beta, C, ldc);
+}
+
 template <>
 void matmul<platform::CPUPlace, float>(
     const platform::DeviceContext& context, const framework::Tensor& matrix_a,

paddle/operators/math/math_function.cu

@@ -63,6 +63,42 @@ void gemm<platform::GPUPlace, double>(const platform::DeviceContext& context,
       cuTransB, cuTransA, N, M, K, &alpha, B, ldb, A, lda, &beta, C, N));
 }
 
+template <>
+void gemm<platform::GPUPlace, float>(const platform::DeviceContext& context,
+                                     const bool transA, const bool transB,
+                                     const int M, const int N, const int K,
+                                     const float alpha, const float* A,
+                                     const int lda, const float* B,
+                                     const int ldb, const float beta, float* C,
+                                     const int ldc) {
+  // Note that cublas follows fortran order, so the order is different from
+  // the cblas convention.
+  cublasOperation_t cuTransA = transA == false ? CUBLAS_OP_N : CUBLAS_OP_T;
+  cublasOperation_t cuTransB = transB == false ? CUBLAS_OP_N : CUBLAS_OP_T;
+  PADDLE_ENFORCE(platform::dynload::cublasSgemm(
+      reinterpret_cast<const platform::CUDADeviceContext&>(context)
+          .cublas_handle(),
+      cuTransB, cuTransA, N, M, K, &alpha, B, ldb, A, lda, &beta, C, ldc));
+}
+
+template <>
+void gemm<platform::GPUPlace, double>(const platform::DeviceContext& context,
+                                      const bool transA, const bool transB,
+                                      const int M, const int N, const int K,
+                                      const double alpha, const double* A,
+                                      const int lda, const double* B,
+                                      const int ldb, const double beta,
+                                      double* C, const int ldc) {
+  // Note that cublas follows fortran order, so the order is different from
+  // the cblas convention.
+  cublasOperation_t cuTransA = transA == false ? CUBLAS_OP_N : CUBLAS_OP_T;
+  cublasOperation_t cuTransB = transB == false ? CUBLAS_OP_N : CUBLAS_OP_T;
+  PADDLE_ENFORCE(platform::dynload::cublasDgemm(
+      reinterpret_cast<const platform::CUDADeviceContext&>(context)
+          .cublas_handle(),
+      cuTransB, cuTransA, N, M, K, &alpha, B, ldb, A, lda, &beta, C, ldc));
+}
+
 template <>
 void matmul<platform::GPUPlace, float>(
     const platform::DeviceContext& context, const framework::Tensor& matrix_a,

paddle/operators/math/math_function.h

@@ -70,6 +70,13 @@ void gemm(const platform::DeviceContext& context, const CBLAS_TRANSPOSE transA,
           const CBLAS_TRANSPOSE transB, const int M, const int N, const int K,
           const T alpha, const T* A, const T* B, const T beta, T* C);
 
+// gemm wrapper with stride args for matrix uncontinuous in memory
+template <typename Place, typename T>
+void gemm(const platform::DeviceContext& context, const bool transA,
+          const bool transB, const int M, const int N, const int K,
+          const T alpha, const T* A, const int lda, const T* B, const int ldb,
+          const T beta, T* C, const int ldc);
+
 // matrix multiply with continuous memory
 template <typename Place, typename T>
 void matmul(const platform::DeviceContext& context,

paddle/operators/math/math_function_test.cc

@@ -72,4 +72,174 @@ TEST(math_function, trans_mul_notrans) {
   EXPECT_EQ(out_ptr[8], 29);
   delete gpu_place;
 }
+
+TEST(math_function, gemm_notrans_cublas) {
+  paddle::framework::Tensor input1;
+  paddle::framework::Tensor input2;
+  paddle::framework::Tensor input3;
+  paddle::framework::Tensor input1_gpu;
+  paddle::framework::Tensor input2_gpu;
+  paddle::framework::Tensor input3_gpu;
+
+  int m = 2;
+  int n = 3;
+  int k = 3;
+  auto* cpu_place = new paddle::platform::CPUPlace();
+  float* input1_ptr = input1.mutable_data<float>({2, 3}, *cpu_place);
+  float arr1[6] = {0, 1, 2, 3, 4, 5};
+  memcpy(input1_ptr, arr1, 6 * sizeof(float));
+  float* input2_ptr = input2.mutable_data<float>({3, 4}, *cpu_place);
+  float arr2[12] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
+  memcpy(input2_ptr, arr2, 12 * sizeof(float));
+  float* input3_ptr = input3.mutable_data<float>({2, 4}, *cpu_place);
+  float arr3[8] = {0, 1, 2, 3, 4, 5, 6, 7};
+  memcpy(input3_ptr, arr3, 8 * sizeof(float));
+
+  auto* gpu_place = new paddle::platform::GPUPlace(0);
+  paddle::platform::CUDADeviceContext context(*gpu_place);
+
+  input1_gpu.CopyFrom<float>(input1, *gpu_place);
+  input2_gpu.CopyFrom<float>(input2, *gpu_place);
+  input3_gpu.CopyFrom<float>(input3, *gpu_place);
+  float* a = input1_gpu.data<float>();
+  float* b = input2_gpu.data<float>();
+  float* c = input3_gpu.mutable_data<float>(*gpu_place);
+
+  paddle::operators::math::gemm<paddle::platform::GPUPlace, float>(
+      context, false, false, m, n, k, 1, a, 3, b + 1, 4, 1, c + 1, 4);
+
+  input3.CopyFrom<float>(input3_gpu, *cpu_place);
+
+  // numpy code:
+  // a = np.arange(6).reshape(2, 3)
+  // b = np.arange(12).reshape(3, 4)[:, 1:]
+  // c = np.arange(8).reshape(2, 4)[:, 1:]
+  // out = np.arange(8).reshape(2, 4)
+  // out[:, 1:] = np.dot(a, b) + c
+  EXPECT_EQ(input3_ptr[0], 0);
+  EXPECT_EQ(input3_ptr[1], 24);
+  EXPECT_EQ(input3_ptr[2], 28);
+  EXPECT_EQ(input3_ptr[3], 32);
+  EXPECT_EQ(input3_ptr[4], 4);
+  EXPECT_EQ(input3_ptr[5], 73);
+  EXPECT_EQ(input3_ptr[6], 86);
+  EXPECT_EQ(input3_ptr[7], 99);
+  delete gpu_place;
+}
+
+TEST(math_function, gemm_trans_cublas) {
+  paddle::framework::Tensor input1;
+  paddle::framework::Tensor input2;
+  paddle::framework::Tensor input3;
+  paddle::framework::Tensor input1_gpu;
+  paddle::framework::Tensor input2_gpu;
+  paddle::framework::Tensor input3_gpu;
+
+  int m = 2;
+  int n = 3;
+  int k = 3;
+  auto* cpu_place = new paddle::platform::CPUPlace();
+  float* input1_ptr = input1.mutable_data<float>({2, 3}, *cpu_place);
+  float arr1[6] = {0, 1, 2, 3, 4, 5};
+  memcpy(input1_ptr, arr1, 6 * sizeof(float));
+  float* input2_ptr = input2.mutable_data<float>({4, 3}, *cpu_place);
+  float arr2[12] = {0, 4, 8, 1, 5, 9, 2, 6, 10, 3, 7, 11};
+  memcpy(input2_ptr, arr2, 12 * sizeof(float));
+  float* input3_ptr = input3.mutable_data<float>({2, 4}, *cpu_place);
+  float arr3[8] = {0, 1, 2, 3, 4, 5, 6, 7};
+  memcpy(input3_ptr, arr3, 8 * sizeof(float));
+
+  auto* gpu_place = new paddle::platform::GPUPlace(0);
+  paddle::platform::CUDADeviceContext context(*gpu_place);
+
+  input1_gpu.CopyFrom<float>(input1, *gpu_place);
+  input2_gpu.CopyFrom<float>(input2, *gpu_place);
+  input3_gpu.CopyFrom<float>(input3, *gpu_place);
+  float* a = input1_gpu.data<float>();
+  float* b = input2_gpu.data<float>();
+  float* c = input3_gpu.mutable_data<float>(*gpu_place);
+
+  paddle::operators::math::gemm<paddle::platform::GPUPlace, float>(
+      context, false, true, m, n, k, 1, a, 3, b + 3, 3, 1, c + 1, 4);
+
+  input3.CopyFrom<float>(input3_gpu, *cpu_place);
+
+  EXPECT_EQ(input3_ptr[0], 0);
+  EXPECT_EQ(input3_ptr[1], 24);
+  EXPECT_EQ(input3_ptr[2], 28);
+  EXPECT_EQ(input3_ptr[3], 32);
+  EXPECT_EQ(input3_ptr[4], 4);
+  EXPECT_EQ(input3_ptr[5], 73);
+  EXPECT_EQ(input3_ptr[6], 86);
+  EXPECT_EQ(input3_ptr[7], 99);
+  delete gpu_place;
+}
 #endif
+
+TEST(math_function, gemm_notrans_cblas) {
+  paddle::framework::Tensor input1;
+  paddle::framework::Tensor input2;
+  paddle::framework::Tensor input3;
+
+  int m = 2;
+  int n = 3;
+  int k = 3;
+  auto* cpu_place = new paddle::platform::CPUPlace();
+  float* input1_ptr = input1.mutable_data<float>({2, 3}, *cpu_place);
+  float arr1[6] = {0, 1, 2, 3, 4, 5};
+  memcpy(input1_ptr, arr1, 6 * sizeof(float));
+  float* input2_ptr = input2.mutable_data<float>({3, 4}, *cpu_place);
+  float arr2[12] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
+  memcpy(input2_ptr, arr2, 12 * sizeof(float));
+  float* input3_ptr = input3.mutable_data<float>({2, 4}, *cpu_place);
+  float arr3[8] = {0, 1, 2, 3, 4, 5, 6, 7};
+  memcpy(input3_ptr, arr3, 8 * sizeof(float));
+
+  paddle::platform::CPUDeviceContext context(*cpu_place);
+  paddle::operators::math::gemm<paddle::platform::CPUPlace, float>(
+      context, false, false, m, n, k, 1, input1_ptr, 3, input2_ptr + 1, 4, 1,
+      input3_ptr + 1, 4);
+
+  EXPECT_EQ(input3_ptr[0], 0);
+  EXPECT_EQ(input3_ptr[1], 24);
+  EXPECT_EQ(input3_ptr[2], 28);
+  EXPECT_EQ(input3_ptr[3], 32);
+  EXPECT_EQ(input3_ptr[4], 4);
+  EXPECT_EQ(input3_ptr[5], 73);
+  EXPECT_EQ(input3_ptr[6], 86);
+  EXPECT_EQ(input3_ptr[7], 99);
+}
+
+TEST(math_function, gemm_trans_clbas) {
+  paddle::framework::Tensor input1;
+  paddle::framework::Tensor input2;
+  paddle::framework::Tensor input3;
+
+  int m = 2;
+  int n = 3;
+  int k = 3;
+  auto* cpu_place = new paddle::platform::CPUPlace();
+  float* input1_ptr = input1.mutable_data<float>({2, 3}, *cpu_place);
+  float arr1[6] = {0, 1, 2, 3, 4, 5};
+  memcpy(input1_ptr, arr1, 6 * sizeof(float));
+  float* input2_ptr = input2.mutable_data<float>({4, 3}, *cpu_place);
+  float arr2[12] = {0, 4, 8, 1, 5, 9, 2, 6, 10, 3, 7, 11};
+  memcpy(input2_ptr, arr2, 12 * sizeof(float));
+  float* input3_ptr = input3.mutable_data<float>({2, 4}, *cpu_place);
+  float arr3[8] = {0, 1, 2, 3, 4, 5, 6, 7};
+  memcpy(input3_ptr, arr3, 8 * sizeof(float));
+
+  paddle::platform::CPUDeviceContext context(*cpu_place);
+  paddle::operators::math::gemm<paddle::platform::CPUPlace, float>(
+      context, false, true, m, n, k, 1, input1_ptr, 3, input2_ptr + 3, 3, 1,
+      input3_ptr + 1, 4);
+
+  EXPECT_EQ(input3_ptr[0], 0);
+  EXPECT_EQ(input3_ptr[1], 24);
+  EXPECT_EQ(input3_ptr[2], 28);
+  EXPECT_EQ(input3_ptr[3], 32);
+  EXPECT_EQ(input3_ptr[4], 4);
+  EXPECT_EQ(input3_ptr[5], 73);
+  EXPECT_EQ(input3_ptr[6], 86);
+  EXPECT_EQ(input3_ptr[7], 99);
+}

paddle/operators/multiplex_op.cc

@@ -25,24 +25,30 @@ class MultiplexOp : public framework::OperatorWithKernel {
 
  protected:
   void InferShape(const framework::InferShapeContext &ctx) const override {
+    PADDLE_ENFORCE_NOT_NULL(ctx.InputVar("Ids"),
+                            "Input(Ids) shouldn't be null.");
     PADDLE_ENFORCE(!ctx.MultiInputVar("X").empty(),
-                   "Input(X) should not be null.");
+                   "MultiInput(X) shouldn't be empty.");
     PADDLE_ENFORCE_NOT_NULL(ctx.OutputVar("Out"),
                             "Output(Out) shouldn't be null.");
+    auto ids_dim = ctx.Input<Tensor>("Ids")->dims();
+    PADDLE_ENFORCE(
+        ids_dim.size() == 2 && ids_dim[1] == 1,
+        "The index tensor must be a vector with size batchSize x 1.");
+
     auto ins = ctx.MultiInput<Tensor>("X");
     auto *out = ctx.Output<Tensor>("Out");
     auto num_ins = ins.size();
-    PADDLE_ENFORCE(num_ins > 2,
-                   "multiplex operator should have more than 2 inputs.");
-    PADDLE_ENFORCE_EQ(ins[0]->dims().size(), 1,
-                      "The first input must be a index vector.");
-    auto in_dim = ins[1]->dims();
+    PADDLE_ENFORCE(num_ins > 1,
+                   "multiplex operator should have more than "
+                   "one candidate input tensors.");
 
-    for (size_t i = 2; i < num_ins; i++) {
+    auto in_dim = ins[0]->dims();
+    PADDLE_ENFORCE(in_dim.size() == 2, "Candidate tensors must be matrix.");
+    for (size_t i = 1; i < num_ins; i++) {
       auto dim = ins[i]->dims();
       PADDLE_ENFORCE(in_dim == dim,
-                     "All the input tensors except the first one must have the "
-                     "same size.");
+                     "All the candidate tensors must have the same size.");
     }
     out->Resize(in_dim);
   }
@@ -53,25 +59,26 @@ class MultiplexOpMaker : public framework::OpProtoAndCheckerMaker {
   MultiplexOpMaker(framework::OpProto *proto,
                    framework::OpAttrChecker *op_checker)
       : OpProtoAndCheckerMaker(proto, op_checker) {
-    AddInput("X", "The input tensors of multiplex operator.").AsDuplicable();
+    AddInput("Ids", "The index tensor of multiplex operator.");
+    AddInput("X", "The candidate tensors of multiplex operator.")
+        .AsDuplicable();
     AddOutput("Out", "The output tensor of multiplex operator.");
     AddComment(R"DOC(Multiplex operator
 
 Multiplex multiple tensors according to the index provided by the first
 input tensor.
 
-ins[0]: the index tensor.
-ins[1:N]: the candidate output tensors.
+Ids: the index tensor.
+X[0 : N - 1]: the candidate tensors for output (N >= 2).
 For each index i from 0 to batchSize - 1, the output is the i-th row of the
-the (index[i] + 1)-th tensor.
+the (Ids[i])-th tensor.
 
 For i-th row of the output tensor:
 
-y[i][j] = x_{k}[i][j], j = 0,1, ... , (x_{1}.width - 1)
+y[i][j] = x_{k}[i][j], j = 0,1, ... , (x_{0}.width - 1)
 
 where y is the output tensor. `x_{k}` is the k-th input tensor
-and `k = x{0}[i] + 1`.
-
+and `k = Ids[i]`.
 )DOC");
   }
 };
@@ -90,8 +97,8 @@ class MultiplexGradOp : public framework::OperatorWithKernel {
                             "Input(Out@GRAD) shouldn't be null.");
     auto d_ins = ctx.MultiOutput<Tensor>(framework::GradVarName("X"));
     auto ins = ctx.MultiInput<Tensor>("X");
-    // don't compute gradient for index (ins[0])
-    for (size_t i = 1; i < ins.size(); i++) {
+    // No need to compute gradient for Input(Ids)
+    for (size_t i = 0; i < ins.size(); i++) {
       if (d_ins[i]) {
         d_ins[i]->Resize(ins[i]->dims());
       }

paddle/operators/multiplex_op.cu

@@ -25,21 +25,23 @@ class MultiplexGPUKernel : public framework::OpKernel {
  public:
   void Compute(const framework::ExecutionContext& ctx) const {
     auto ins = ctx.MultiInput<Tensor>("X");
+    auto* ids = ctx.Input<Tensor>("Ids");
     auto* out = ctx.Output<Tensor>("Out");
     out->mutable_data<T>(ctx.GetPlace());
 
-    auto rows = ins[1]->dims()[0];
-    auto cols = ins[1]->dims()[1];
+    auto rows = ins[0]->dims()[0];
+    auto cols = ins[0]->dims()[1];
     // copy index to cpu
     Tensor index_t_cpu;
-    index_t_cpu.CopyFrom<T>(*(ins[0]), platform::CPUPlace());
-    auto* index = index_t_cpu.data<T>();
+    index_t_cpu.CopyFrom<int32_t>(*ids, platform::CPUPlace());
+    auto* index = index_t_cpu.data<int32_t>();
     auto stream = reinterpret_cast<const platform::CUDADeviceContext&>(
                       ctx.device_context())
                       .stream();
     Place place = boost::get<Place>(ctx.GetPlace());
     for (auto i = 0; i < rows; i++) {
-      size_t k = (size_t)index[i] + 1;
+      int32_t k = index[i];
+      PADDLE_ENFORCE_GE(k, 0, "index must be nonnegative.");
       PADDLE_ENFORCE_LT(k, ins.size(),
                         "index exceeds the number of candidate tensors.");
       memory::Copy(place, out->data<T>() + i * cols, place,
@@ -54,8 +56,9 @@ class MultiplexGradGPUKernel : public framework::OpKernel {
   void Compute(const framework::ExecutionContext& ctx) const {
     auto* d_out = ctx.Input<Tensor>(framework::GradVarName("Out"));
     auto ins = ctx.MultiInput<Tensor>("X");
+    auto* ids = ctx.Input<Tensor>("Ids");
     auto d_ins = ctx.MultiOutput<Tensor>(framework::GradVarName("X"));
-    for (size_t i = 1; i < d_ins.size(); i++) {
+    for (size_t i = 0; i < d_ins.size(); i++) {
       if (d_ins[i]) {
         d_ins[i]->mutable_data<T>(ctx.GetPlace());
         auto t = framework::EigenVector<T>::Flatten(*d_ins[i]);
@@ -63,19 +66,19 @@ class MultiplexGradGPUKernel : public framework::OpKernel {
       }
     }
 
-    auto rows = ins[1]->dims()[0];
-    auto cols = ins[1]->dims()[1];
+    auto rows = ins[0]->dims()[0];
+    auto cols = ins[0]->dims()[1];
     // copy index to cpu
     Tensor index_t_cpu;
-    index_t_cpu.CopyFrom<T>(*(ins[0]), platform::CPUPlace());
-    auto* index = index_t_cpu.data<T>();
+    index_t_cpu.CopyFrom<int32_t>(*ids, platform::CPUPlace());
+    auto* index = index_t_cpu.data<int32_t>();
 
     auto stream = reinterpret_cast<const platform::CUDADeviceContext&>(
                       ctx.device_context())
                       .stream();
     Place place = boost::get<Place>(ctx.GetPlace());
     for (auto i = 0; i < rows; i++) {
-      size_t k = (size_t)index[i] + 1;
+      size_t k = static_cast<size_t>(index[i]);
       if (d_ins[k]) {
         memory::Copy(place, d_ins[k]->data<T>() + i * cols, place,
                      d_out->data<T>() + i * cols, cols * sizeof(T), stream);

paddle/operators/multiplex_op.h

@@ -27,17 +27,19 @@ class MultiplexCPUKernel : public framework::OpKernel {
  public:
   void Compute(const framework::ExecutionContext& ctx) const {
     auto ins = ctx.MultiInput<framework::Tensor>("X");
+    auto ids = ctx.Input<framework::Tensor>("Ids");
     auto* out = ctx.Output<framework::Tensor>("Out");
 
     out->mutable_data<T>(ctx.GetPlace());
 
-    auto rows = ins[1]->dims()[0];
-    auto cols = ins[1]->dims()[1];
-    auto* index = ins[0]->data<T>();
+    auto rows = ins[0]->dims()[0];
+    auto cols = ins[0]->dims()[1];
+    auto index = ids->data<int32_t>();
     Place place = boost::get<Place>(ctx.GetPlace());
     for (auto i = 0; i < rows; i++) {
-      size_t k = (size_t)index[i] + 1;
-      PADDLE_ENFORCE_LT(k, ins.size(),
+      int32_t k = index[i];
+      PADDLE_ENFORCE_GE(k, 0, "index must be nonnegative.");
+      PADDLE_ENFORCE_LT(static_cast<size_t>(k), ins.size(),
                         "index exceeds the number of candidate tensors.");
       memory::Copy(place, out->data<T>() + i * cols, place,
                    ins[k]->data<T>() + i * cols, cols * sizeof(T));
@@ -50,10 +52,11 @@ class MultiplexGradCPUKernel : public framework::OpKernel {
  public:
   void Compute(const framework::ExecutionContext& ctx) const {
     auto* d_out = ctx.Input<framework::Tensor>(framework::GradVarName("Out"));
+    auto* ids = ctx.Input<framework::Tensor>("Ids");
     auto ins = ctx.MultiInput<framework::Tensor>("X");
     auto d_ins =
         ctx.MultiOutput<framework::Tensor>(framework::GradVarName("X"));
-    for (size_t i = 1; i < d_ins.size(); i++) {
+    for (size_t i = 0; i < d_ins.size(); i++) {
       if (d_ins[i]) {
         d_ins[i]->mutable_data<T>(ctx.GetPlace());
         auto t = framework::EigenVector<T>::Flatten(*d_ins[i]);
@@ -61,12 +64,12 @@ class MultiplexGradCPUKernel : public framework::OpKernel {
       }
     }
 
-    auto rows = ins[1]->dims()[0];
-    auto cols = ins[1]->dims()[1];
-    auto* index = ins[0]->data<T>();
+    auto rows = ins[0]->dims()[0];
+    auto cols = ins[0]->dims()[1];
+    auto* index = ids->data<int32_t>();
     Place place = boost::get<Place>(ctx.GetPlace());
     for (auto i = 0; i < rows; i++) {
-      size_t k = (size_t)index[i] + 1;
+      size_t k = static_cast<size_t>(index[i]);
       if (d_ins[k]) {
         memory::Copy(place, d_ins[k]->data<T>() + i * cols, place,
                      d_out->data<T>() + i * cols, cols * sizeof(T));
@@ -74,5 +77,5 @@ class MultiplexGradCPUKernel : public framework::OpKernel {
     }
   }
 };
-}
-}
+}  // namespace operators
+}  // namespace paddle

python/paddle/trainer_config_helpers/layers.py

@@ -921,7 +921,7 @@ def data_layer(name, size, depth=None, height=None, width=None,
 
         data = data_layer(name="input", size=1000)
 
-    :param name: The name of this layer. It is optional.
+    :param name: The name of this layer.
     :type name: basestring
     :param size: Size of this data layer.
     :type size: int
@@ -3668,6 +3668,7 @@ def gru_step_naive_layer(input,
     :param param_attr:
     :param layer_attr:
     :return:
+    :rtype: LayerOutput
     """
     if input.size % 3 != 0:
         raise ValueError("GruStep input size must be divided by 3")

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

@@ -6,20 +6,22 @@ from op_test import OpTest
 class TestMultiplexOp(OpTest):
     def setUp(self):
         self.op_type = "multiplex"
-        rows = 3
-        index = np.array([3, 1, 0])
+        rows = 4
+        index = np.arange(0, rows).astype('int32')
+        np.random.shuffle(index)
+        index = np.reshape(index, (rows, 1))
         ins1 = np.random.random((rows, 10)).astype("float32")
         ins2 = np.random.random((rows, 10)).astype("float32")
         ins3 = np.random.random((rows, 10)).astype("float32")
         ins4 = np.random.random((rows, 10)).astype("float32")
         self.inputs = {
-            'X': [('index', index), ('x1', ins1), ('x2', ins2), ('x3', ins3),
-                  ('x4', ins4)]
+            'Ids': index,
+            'X': [('x1', ins1), ('x2', ins2), ('x3', ins3), ('x4', ins4)]
         }
         # multiplex output
         output = np.zeros_like(ins1)
         for i in range(0, rows):
-            k = index[i] + 1
+            k = index[i][0]
             output[i] = self.inputs['X'][k][1][i]
         self.outputs = {'Out': output}