add backward function of ConverDataType

source/network/XBackwardData.cpp

+/* NiuTrans.Tensor - an open-source tensor library
+ * Copyright (C) 2018, Natural Language Processing Lab, Northestern University.
+ * All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * backward computation for data operation
+ * $Created by: Xu Chen (email: hello_master1954@163.com) 2018-12-26
+ */
+
+#include "XNoder.h"
+#include "XBackwardData.h"
+#include "../tensor/XName.h"
+#include "../tensor/XUtility.h"
+#include "../tensor/core/CHeader.h"
+#include "../tensor/core/getandset/SetData.h"
+
+namespace nts{
+
+/* compute dE/dx of a node */
+void XDataGrad::MakeGrad(XTensor * node, bool isEfficent)
+{
+    CheckNTErrors(node->grad != NULL, "No gradient found!");
+
+    XLink &income = node->income;
+    int operID = income.typeID;
+
+    if(operID == GETANDSET_CONVERTDATATYPE)
+        GradConvertDataType(node, isEfficent);
+    else if(operID == GETANDSET_INDEXTOONEHOT)
+        GradIndexToOnehot(node, isEfficent);
+    else if(operID == GETANDSET_ONEHOTTOINDEX)
+        GradOnehotToIndex(node, isEfficent);
+    else{
+        ShowNTErrors("TODO!");
+    }
+}
+
+/* indicates whether the node is for a data operation */
+bool XDataGrad::IsDataOP(XTensor * node)
+{
+    XLink &income = node->income;
+    return (income.typeID & DATA_BASE) != 0;
+}
+
+/* 
+gradient computation for convert datatype
+for
+b = converdatatype(a) 
+we have
+dE/da = convertdatatype(b)
+>> node - the node (c) for backward computation
+>> isEfficient - indicates whether the computation is in
+                 an efficient manner
+*/
+void XDataGrad::GradConvertDataType(XTensor * node, bool isEfficent)
+{
+    XLink &income = node->income;
+    CheckNTErrors(income.tailNum > 0, "Wrong input tensor number for ConvertDataType!");
+
+    XTensor * input = income.tails[0];
+
+    XNoder::MakeGrad(input);
+    _ConvertDataType(node->grad, input->grad);
+}
+
+/* 
+gradient computation for OnehotToIndex
+for
+b = OnehotToIndex(a) 
+we have
+dE/da = IndexToOnehot(b)
+>> node - the node (c) for backward computation
+>> isEfficient - indicates whether the computation is in
+                 an efficient manner
+*/
+void XDataGrad::GradIndexToOnehot(XTensor * node, bool isEfficent)
+{
+    XLink &income = node->income;
+    CheckNTErrors(income.tailNum > 0, "Wrong input tensor number for IndexToOnehot!");
+
+    XTensor * input = income.tails[0];
+
+    XNoder::MakeGrad(input);
+
+}
+
+} // namespace nts(NiuTrans.Tensor)

source/network/XBackwardData.h

+/* NiuTrans.Tensor - an open-source tensor library
+ * Copyright (C) 2018, Natural Language Processing Lab, Northestern University.
+ * All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * backward computation for data operation
+ * $Created by: Xu Chen (email: hello_master1954@163.com) 2018-12-26
+ */
+
+#include "../tensor/XTensor.h"
+#include "../tensor/function/FHeader.h"
+
+#ifndef __XBACKWARDDATA_H__
+#define __XBACKWARDDATA_H__
+
+namespace nts{
+
+/* this class computes the gradient for tensor data operation given a node */
+class XDataGrad
+{
+public:
+    /* compute dE/dx of a node */
+    static
+    void MakeGrad(XTensor * node, bool isEfficent);
+
+    /* indicates whether the node is for a shaping operation */
+    static
+    bool IsDataOP(XTensor * node);
+
+private:
+    
+    /* gradient computation for ConverDataType: b = converdatatype(a, datatype) */
+    static
+    void GradConvertDataType(XTensor * node, bool isEfficent);
+
+    /* gradient computation for IndexToOnehot: b = indextoonehot(a, num) */
+    static
+    void GradIndexToOnehot(XTensor * node, bool isEfficent);
+
+    /* gradient computation for OnehotToIndex: b = onehottoindex(a, num) */
+    static
+    void GradOnehotToIndex(XTensor * node, bool isEfficent);
+};
+
+} // namespace nts(NiuTrans.Tensor)
+
+#endif
\ No newline at end of file

source/network/XBackwardShape.cpp

@@ -62,7 +62,7 @@ void XShapeGrad::MakeGrad(XTensor * node, bool isEfficent)
     }
 }
 
-/* indicates whether the node is for a math operation */
+/* indicates whether the node is for a shape operation */
 bool XShapeGrad::IsShapeOP(XTensor * node)
 {
     XLink &income = node->income;

source/tensor/XName.cpp

@@ -97,7 +97,13 @@ const char * GetOPName(int type)
             return "R_REDUCEVARIANCE";
     }
     else if ((type & DATA_BASE) != 0){
-        if (type == GETANDSET_SELECT)
+        if (type == GETANDSET_CONVERTDATATYPE)
+            return "G_CONVERTDATATYPE";
+        else if (type == GETANDSET_INDEXTOONEHOT)
+            return "G_INDEXTOONEHOT";
+        else if (type == GETANDSET_ONEHOTTOINDEX)
+            return "G_ONEHOTTOINDEX";
+        else if (type == GETANDSET_SELECT)
             return "G_SELECT";
         else if (type == MOVEMENT_COPYINDEXED)
             return "M_COPYINDEXED";

source/tensor/XName.h

@@ -72,7 +72,10 @@ namespace nts { // namespace nts(NiuTrans.Tensor)
 /* data and shape related operations */
 #define DATA_BASE               MATH_BASE * 2
 #define GETANDSET               DATA_BASE + 1
-#define GETANDSET_SELECT        GETANDSET + 1
+#define GETANDSET_CONVERTDATATYPE GETANDSET + 1
+#define GETANDSET_INDEXTOONEHOT GETANDSET_CONVERTDATATYPE + 1
+#define GETANDSET_ONEHOTTOINDEX GETANDSET_INDEXTOONEHOT + 1
+#define GETANDSET_SELECT        GETANDSET_ONEHOTTOINDEX + 1
 
 #define MOVEMENT                GETANDSET_SELECT + 1
 #define MOVEMENT_COPYINDEXED    MOVEMENT + 1

source/tensor/core/getandset/ConvertDataType.cpp

@@ -20,13 +20,16 @@
 */
 
 #include "../../XTensor.h"
+#include "../../XName.h"
 #include "ConvertDataType.h"
 #include "ConvertDataType.cuh"
+#include "../movement/CopyValues.h"
 
 namespace nts { // namespace nts(NiuTrans.Tensor)
 
 /*
 convert data type
+
 >> input - input tensor
 >> output - output tensor
 */
@@ -60,28 +63,34 @@ void _ConvertDataType(const XTensor * input, XTensor * output)
 
 }
 
-
 /*
 convert data type (return an XTensor structure) 
 make a new tensor to keep the result and return it
 
 >> input - input tensor
->> output - output tensor
+<< return - output tensor with the specified data type
 */
 XTensor ConvertDataType(const XTensor & input, TENSOR_DATA_TYPE dataType)
 {
+    if (input.dataType == dataType) {
+        XTensor output;
+        output = CopyValues(input);
+
+        return output;
+    }
+
     int order = input.order;
     
     float dr = (!input.isSparse) ? 1.0F : input.denseRatio;
     XTensor output(order, input.dimSize, dataType, dr, input.devID, input.mem);
     output.SetTMPFlag();
 
-
-    _Gather(&s, &t, &index);
+    _ConvertDataType(&input, &output);
 
     /* tensor connection */
-    XLink::MakeLink(&s, &index, &t, MOVEMENT_GATHER);
-}
+    XLink::MakeLink(&input, NULL, &output, GETANDSET_CONVERTDATATYPE);
 
+    return output;
+}
 
 } // namespace nts(NiuTrans.Tensor)
\ No newline at end of file

source/tensor/core/getandset/ConvertDataType.h

@@ -31,7 +31,7 @@ namespace nts { // namespace nts(NiuTrans.Tensor)
 void _ConvertDataType(const XTensor * input, XTensor * output);
 
 /* convert data type (return an XTensor structure) */
-XTensor ConvertDataType(const XTensor * input, TENSOR_DATA_TYPE dataType);
+XTensor ConvertDataType(const XTensor & input, TENSOR_DATA_TYPE dataType);
 
 } // namespace nts(NiuTrans.Tensor)