[tmva][sofie] Add Softmax operator

Use initial code from GSOC candidate student Neel Shah

Author: lmoneta

tmva/sofie/inc/TMVA/ROperator_Softmax.hxx

@@ -0,0 +1,76 @@
+#ifndef TMVA_SOFIE_ROPERATOR_Softmax
+ #define TMVA_SOFIE_ROPERATOR_Softmax
+
+ #include "TMVA/SOFIE_common.hxx"
+ #include "TMVA/ROperator.hxx"
+ #include "TMVA/RModel.hxx"
+
+ #include <sstream>
+
+ namespace TMVA{
+ namespace Experimental{
+ namespace SOFIE{
+
+ template <typename T>
+ class ROperator_Softmax final : public ROperator
+ {
+
+ private:
+
+    std::string fNX;
+    std::string fNY;
+    std::vector<size_t> fShape;
+
+ public:
+    ROperator_Softmax(){}
+    ROperator_Softmax(std::string nameX, std::string nameY):
+       fNX(UTILITY::Clean_name(nameX)), fNY(UTILITY::Clean_name(nameY)){}
+
+    std::vector<ETensorType> TypeInference(std::vector<ETensorType> input){
+       return input;
+    }
+
+    std::vector<std::vector<size_t>> ShapeInference(std::vector<std::vector<size_t>> input){
+       auto ret = input; //suggest copy to compiler
+       return ret;
+    }
+
+    void Initialize(RModel& model){
+       if (model.CheckIfTensorAlreadyExist(fNX) == false){   //input must be a graph input, or already initialized intermediate tensor
+          throw std::runtime_error("TMVA SOFIE Softmax Op Input Tensor is not found in model");
+       }
+       fShape = model.GetTensorShape(fNX);
+       model.AddIntermediateTensor(fNY, model.GetTensorType(fNX), fShape);
+    }
+
+
+    std::string Generate(std::string OpName){
+       OpName = "op_" + OpName;
+       if (fShape.empty()){
+          throw std::runtime_error("TMVA SOFIE Transpose Softmax called to Generate without being initialized first");
+       }
+       std::stringstream out;
+       int length = 1;
+       for(auto& i: fShape){
+          length *= i;
+       }
+       out << "\n//------ SOFTMAX\n";
+       out << SP << "double sum = 0.0;\n";
+       out << SP << "for (int id = 0; id < " << length << " ; id++){\n";
+       out << SP << SP << "tensor_" << fNY << "[id] = std::exp( - tensor_"  << fNX << "[id]);\n";
+       out << SP << SP << "sum += tensor_" << fNY << "[id];\n";
+       out << SP << "}\n";
+       out << SP << "for (int id = 0; id < " << length << " ; id++){\n";
+       out << SP << SP << "tensor_" << fNY << "[id] /= sum;\n";
+       out << SP << "}\n";
+       return out.str();
+    }
+
+ };
+
+ }//SOFIE
+ }//Experimental
+ }//TMVA
+
+
+ #endif //TMVA_SOFIE_ROPERATOR_Softmax