From e23c1fee66b80c8faf1c01840ddc10ff64e0187e Mon Sep 17 00:00:00 2001 From: Abhinav Arora Date: Tue, 17 Oct 2017 16:41:18 -0700 Subject: [PATCH] Correcting some grammatical mistakes in SelectedRows Document (#4872) --- doc/design/selected_rows.md | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/doc/design/selected_rows.md b/doc/design/selected_rows.md index 9e6f3b20cbc..1a98839a957 100644 --- a/doc/design/selected_rows.md +++ b/doc/design/selected_rows.md @@ -1,6 +1,6 @@ # Design Doc: Selected Rows -`SelectedRows` is a kind of sparse tensor data type, which is designed to support `embedding` operators. The gradient of embedding table is a sparse tensor. Only a few rows are non-zero values in that tensor. It is straightforward to represent the sparse tensor by the following sparse tensor data structure: +`SelectedRows` is a type of sparse tensor data type, which is designed to support `embedding` operators. The gradient of embedding table is a sparse tensor. Only a few rows are non-zero values in this tensor. It is straight-forward to represent a sparse tensor by the following sparse tensor data structure: ```cpp class SelectedRows { @@ -11,7 +11,7 @@ class SelectedRows { }; ``` -The field `height_` shows the first dimension of `SelectedRows`. The `rows` are the indices of which rows of `SelectedRows` are non-zeros. The `value_` field is an N-dim tensor and shape is `[rows.size() /* NUM_ROWS */, ...]`, which supplies values for each row. The dimension of `SelectedRows` satisfies `[height_] + value_.shape[1:]`. +The field `height_` is the first dimension of `SelectedRows`. The `rows` are the indices of the non-zero rows of `SelectedRows`. The `value_` field is an N-dim tensor of shape `[rows.size() /* NUM_ROWS */, ...]`, which supplies values for each row. The dimension of `SelectedRows` satisfies `[height_] + value_.shape[1:]`. Suppose that a SelectedRows-typed variable `x` has many rows, but only two of them have values -- row 73 is `[1, 2]` and row 84 is `[3, 4]`, the `SelectedRows` representation would be: @@ -25,7 +25,7 @@ x = SelectedRow { ## SelectedRows in Protobuf -`SelectedRows` is a kind of `Variable`. `VarDesc` in protobuf should describe the `SelectedRows` information. Only the tensor dimension of a `SelectedRows` will be described in compile-time since the `rows_` and `value_` are related to training data. +`SelectedRows` is a type of `Variable`. `VarDesc` in protobuf should describe the `SelectedRows` information. Only the tensor dimension of a `SelectedRows` will be described in compile-time because the `rows_` and `value_` are dependent on the training data. So we use `TensorDesc` to unify `data_type` and `dims`. A LodTensorDesc contains a `TensorDesc` and `lod_level`. The description of `SelectedRows` is a Tensor description. ```proto @@ -54,7 +54,7 @@ message VarDesc { ## InferShape for Selected Rows -Just like `LoD` information, `InferShape` method will inference output tensor type as well. The operator should decide whether its output is a `SelectedRows` or `Dense` tensor. +Just like `LoD` information, `InferShape` method will infer the output tensor type as well. The operator should decide whether its output is a `SelectedRows` or `Dense` tensor. For example, the gradient operator of `TableLookup` will always generate `SelectedRows`. Its `InferShape` method should be like following @@ -68,7 +68,7 @@ void TableLookupGrad::InferShape(context) { ## Sparse Operators -There are several operators should be written to support `SelectedRows`. They are: +There are several operators that need to be written to support `SelectedRows`. These are: -1. Operators which generates `SelectedRows` gradient. e.g. Gradient of `TableLookupOp`. +1. Operators which generate `SelectedRows` gradient. e.g. Gradient of `TableLookupOp`. 2. Optimize operators which support `SelectedRows` gradient. e.g. `SGD` or `AdaGrad` for `SelectedRows`. However, there should be only one `SGD` operator. `OpWithKernel::Run` should select a suitable kernel for both `dense` tensor or `SelectedRows`. -- GitLab