Polish operator documentation (#5356)

* Polish the documentation for uniform_random and top_k ops

* Polishing more operators

paddle/operators/save_op.cc

@@ -163,14 +163,19 @@ class SaveOpProtoMaker : public framework::OpProtoAndCheckerMaker {
   SaveOpProtoMaker(framework::OpProto *proto,
                    framework::OpAttrChecker *op_checker)
       : OpProtoAndCheckerMaker(proto, op_checker) {
-    AddInput("X", "The tensor need to be saved");
-    AddComment(R"DOC(Save operator
-Save operator will serialize and write a tensor variable to disk file.
+    AddInput("X", "(Tensor ) Input tensor to be saved");
+    AddComment(R"DOC(
+Save operator
+
+This operator will serialize and write a tensor variable to file on disk.
 )DOC");
-    AddAttr<bool>("overwrite", "Overwrite the output file if exist")
+    AddAttr<bool>("overwrite",
+                  "(boolean, default true)"
+                  "Overwrite the output file if exist")
         .SetDefault(true);
     AddAttr<std::string>("file_path",
-                         "Variable will be saved to \"file_path\".")
+                         "(string)"
+                         "The \"file_path\" where the variable will be saved.")
         .AddCustomChecker(
             [](const std::string &path) { return !path.empty(); });
   }

paddle/operators/scale_op.cc

@@ -40,13 +40,16 @@ class ScaleOpMaker : public framework::OpProtoAndCheckerMaker {
  public:
   ScaleOpMaker(framework::OpProto *proto, framework::OpAttrChecker *op_checker)
       : OpProtoAndCheckerMaker(proto, op_checker) {
-    AddInput("X", "The input tensor of scale operator.");
-    AddOutput("Out", "The output tensor of scale operator.");
-    AddComment(R"DOC(Scale operator
+    AddInput("X", "(Tensor) Input tensor of scale operator.");
+    AddOutput("Out", "(Tensor) Output tensor of scale operator.");
+    AddComment(R"DOC(
+Scale operator
 
-The equation is: Out = scale*X
+$$Out = scale*X$$
 )DOC");
-    AddAttr<AttrType>("scale", "The scaling factor of the scale operator.")
+    AddAttr<AttrType>("scale",
+                      "(float, default 0)"
+                      "The scaling factor of the scale operator.")
         .SetDefault(1.0);
   }
 };

paddle/operators/sequence_concat_op.cc

@@ -47,19 +47,19 @@ class SequenceConcatOpMaker : public framework::OpProtoAndCheckerMaker {
                         framework::OpAttrChecker* op_checker)
       : OpProtoAndCheckerMaker(proto, op_checker) {
     AddInput("X",
-             "(A vector of LoDTensor), the input is a vector of LoDTensor, "
+             "(vector<LoDTensor>) Input is a vector of LoDTensor, "
              "each of which is a variable-length sequence or nested sequence.")
         .AsDuplicable();
     AddOutput("Out",
-              "(A LoDTensor), the variable-length output of "
+              "(LoDTensor), Variable-length output of "
               "sequence_concat Op.");
     AddAttr<int>("axis",
-                 "(int, default 0)"
-                 "The axis which the inputs will be joined with. "
+                 "(int, default 0) "
+                 "The axis along which the inputs will be joined. "
                  "If axis is 0, the inputs will be joined with LoD index.")
         .SetDefault(0);
     AddAttr<int>("level",
-                 "(int, default 0)"
+                 "(int, default 0) "
                  "The level at which the inputs will be joined. "
                  "If the level is 0, the inputs will be joined at the nested "
                  "sequence level. "
@@ -68,10 +68,12 @@ class SequenceConcatOpMaker : public framework::OpProtoAndCheckerMaker {
                  "The level should be less than the level number of inputs.")
         .SetDefault(0);
     AddComment(R"DOC(
-    The sequence_concat operator concatenates multiple LoDTensors.
-    It only supports sequence (LoD Tensor with level number is 1)
-    or a nested sequence (LoD tensor with level number is 2) as its input.
-    - Case1:
+Sequence Concat operator
+
+The sequence_concat operator concatenates multiple LoDTensors.
+It only supports sequence (LoD Tensor with level number is 1)
+or a nested sequence (LoD tensor with level number is 2) as its input.
+- Case1:
   If the axis is other than 0(here, axis is 1 and level is 1),
   each input should have the same LoD information and the LoD
   information of the output keeps the same as the input.
@@ -80,7 +82,7 @@ class SequenceConcatOpMaker : public framework::OpProtoAndCheckerMaker {
     LoD(x1) = {{0,2,4}, {0,1,2,3,4}}; Dims(x1) = (4,4,4)
     LoD(Out) = {{0,2,4}, {0,1,2,3,4}}; Dims(Out) = (4,7,4)
 
-    - Case2:
+- Case2:
   If the axis is 0(here, leve is 0), the inputs are concatenated along
   time steps, the LoD information of the output need to re-compute.
 
@@ -88,14 +90,14 @@ class SequenceConcatOpMaker : public framework::OpProtoAndCheckerMaker {
     LoD(x1) = {{0,3,5}, {0,1,2,3,5}}; Dims(x1) = (5,3,4)
     LoD(Out) = {{0,5,9}, {0,1,2,3,4,5,6,7,9}}; Dims(Out) = (9,3,4)
 
-    - Case3:
+- Case3:
   If the axis is 0(here, level is 1).
 
     LoD(x0) = {{0,2,4}, {0,1,2,3,4}}; Dims(x0) = (4,3,4)
     LoD(x1) = {{0,3,5}, {0,1,3,4,5}}; Dims(x1) = (5,3,4)
     LoD(Out) = {{0,5,9}, {0,2,5,7,9}}; Dims(Out) = (9,3,4)
 
-    NOTE: The levels of all the inputs should be the same.
+NOTE: The levels of all the inputs should be the same.
     )DOC");
   }
 };

paddle/operators/sgd_op.cc

@@ -45,15 +45,17 @@ class SGDOpMaker : public framework::OpProtoAndCheckerMaker {
  public:
   SGDOpMaker(framework::OpProto* proto, framework::OpAttrChecker* op_checker)
       : OpProtoAndCheckerMaker(proto, op_checker) {
-    AddInput("Param", "Input parameter");
-    AddInput("LearningRate", "Learning rate of SGD");
-    AddInput("Grad", "Input gradient");
-    AddOutput("ParamOut", "output parameter");
+    AddInput("Param", "(Tensor) Input parameter");
+    AddInput("LearningRate", "(Tensor) Learning rate of SGD");
+    AddInput("Grad", "(Tensor) Input gradient");
+    AddOutput("ParamOut", "(Tensor) Output parameter");
     AddComment(R"DOC(
 
-Simplest sgd algorithm.
+SGD operator
 
-param_out = param - learning_rate * grad;
+This operator implements one step of the stochastic gradient descent algorithm.
+
+$$param_out = param - learning_rate * grad$$
 
 )DOC");
   }

paddle/operators/sign_op.cc

@@ -38,9 +38,10 @@ class SignOpMaker : public framework::OpProtoAndCheckerMaker {
       : OpProtoAndCheckerMaker(proto, op_checker) {
     AddInput("X", "(Tensor) Input tensor of sign operator.");
     AddOutput("Out", "(Tensor) Output tensor of sign operator.");
-    AddComment(R"DOC(Sign operator
+    AddComment(R"DOC(
+Sign operator
 
-The equation is: Out = X.sign()
+$$Out = X.sign()$$
 )DOC");
   }
 };

paddle/operators/split_op.cc

@@ -67,11 +67,15 @@ class SplitOpMaker : public framework::OpProtoAndCheckerMaker {
  public:
   SplitOpMaker(framework::OpProto *proto, framework::OpAttrChecker *op_checker)
       : OpProtoAndCheckerMaker(proto, op_checker) {
-    AddInput("X", "the input tensor of split operator.");
-    AddOutput("Out", "the output tensors of split operator.").AsDuplicable();
+    AddInput("X", "(Tensor) Input tensor of the split operator.");
+    AddOutput("Out", "(Tensor) Output tensors of the split operator.")
+        .AsDuplicable();
     AddComment(R"DOC(
-      Split the input tensor into multiple sub-tensors.
-      Example:
+Split operator
+
+This operator splits the input tensor into multiple sub-tensors.
+
+Example:
   Input = [[1,2],
            [3,4],
            [5,6]]
@@ -83,14 +87,18 @@ class SplitOpMaker : public framework::OpProtoAndCheckerMaker {
 
     )DOC");
     AddAttr<std::vector<int>>("sections",
-                              "the length for each"
-                              "output along with the specify axis.")
+                              "(vector<int>) "
+                              "the length of each output along the "
+                              "specified axis.")
         .SetDefault(std::vector<int>{});
     AddAttr<int>("num",
-                 "number of the sub-tensors, it must evenly divide "
+                 "(int, default 0)"
+                 "Number of sub-tensors. This must evenly divide "
                  "Input.dims()[axis]")
         .SetDefault(0);
-    AddAttr<int>("axis", "The axis which the input will be splited on.")
+    AddAttr<int>("axis",
+                 "(int, default 0) "
+                 "The axis which the input will be splited on.")
         .SetDefault(0);
   }
 };

paddle/operators/squared_l2_distance_op.cc

@@ -59,23 +59,26 @@ class SquaredL2DistanceOpMaker : public framework::OpProtoAndCheckerMaker {
   SquaredL2DistanceOpMaker(framework::OpProto* proto,
                            framework::OpAttrChecker* op_checker)
       : OpProtoAndCheckerMaker(proto, op_checker) {
-    AddInput("X", "Input of SquaredL2DistanceOp.");
-    AddInput("Y", "Target of SquaredL2DistanceOp.");
+    AddInput("X", "(Tensor) Input of SquaredL2DistanceOp.");
+    AddInput("Y", "(Tensor) Target of SquaredL2DistanceOp.");
     AddOutput("sub_result",
-              "Buffering substraction result which "
+              "(Tensor) Buffering subtraction result which "
               "will be reused in backward.")
         .AsIntermediate();
-    AddOutput("Out", "Squared l2 distance between input and target.");
+    AddOutput("Out", "(Tensor) Squared l2 distance between input and target.");
     AddComment(R"DOC(
-    SquaredL2DistanceOp will cacluate the squared L2 distance for
-    input and target. Number of distance value equals to the
-    first dimension of input. First dimension of target could be equal to
-    input or to 1. If the first dimension of target is 1, SquaredL2DistanceOp
-    will broadcast target's first dimension to input's first dimension.
-    You can decide whether calculate the gradient of input and target.
-
-    Both the input X and Y can carry the LoD (Level of Details) information,
-    or not. But the output only shares the LoD with input X.
+SquaredL2Distance operator
+
+This operator will cacluate the squared L2 distance for the input and 
+the target. Number of distance value will be equal to the first dimension 
+of input. First dimension of the target could be equal to the input or to 1. 
+If the first dimension of target is 1, the operator will broadcast target's 
+first dimension to input's first dimension. During backward propagation, 
+the user can decide whether to calculate the gradient of the input or 
+the target or both.
+
+Both the input X and Y can carry the LoD (Level of Details) information. 
+However, the output only shares the LoD information with input X.
     )DOC");
   }
 };

paddle/operators/squared_l2_norm_op.cc

@@ -52,13 +52,13 @@ class SquaredL2NormOpMaker : public framework::OpProtoAndCheckerMaker {
                        framework::OpAttrChecker* op_checker)
       : framework::OpProtoAndCheckerMaker(proto, op_checker) {
     AddInput("X", "(Tensor) The input of squared_l2_norm op.");
-    AddOutput("Out", "(Float) The output of squared_l2_norm op.");
+    AddOutput("Out", "(Scalar) The output of squared_l2_norm op.");
     AddComment(R"DOC(
 SquaredL2Norm Operator.
 
 Computes the squared L2 norm of a tensor.
 
-Out = sum (X ** 2)
+$$Out = \sum_{i} X_{i}^2$$
 
 )DOC");
   }

paddle/operators/sum_op.cc

@@ -45,13 +45,15 @@ class SumOpMaker : public framework::OpProtoAndCheckerMaker {
  public:
   SumOpMaker(framework::OpProto* proto, framework::OpAttrChecker* op_checker)
       : OpProtoAndCheckerMaker(proto, op_checker) {
-    AddInput("X", "the input tensors of sum operator.").AsDuplicable();
-    AddOutput("Out", "the output tensor of sum operator.");
+    AddInput("X", "(vector<Tensor>) The input tensors of sum operator.")
+        .AsDuplicable();
+    AddOutput("Out", "(Tensor) The output tensor of sum operator.");
     AddComment(R"DOC(
-Sum the input tensors.
+Sum operator.
 
-All the inputs can carry the LoD (Level of Details) information,
-or not. But the output only shares the LoD with the first input.
+This operators sums the input tensors. All the inputs can carry the 
+LoD (Level of Details) information. However, the output only shares 
+the LoD information with the first input.
 )DOC");
   }
 };