tmva001_RTensor.C File Reference

Detailed Description

This tutorial illustrates the basic features of the RTensor class, RTensor is a std::vector-like container with additional shape information.

The class serves as an interface in C++ between multi-dimensional data and the algorithm such as in machine learning workflows. The interface is similar to Numpy arrays and provides a subset of the functionality.

 
using namespace TMVA::Experimental;
 
void tmva001_RTensor()
{
   // Create RTensor from scratch
   RTensor<float> x({2, 2});
   cout << x << endl;
 
   // Assign some data
   x(0, 0) = 1;
   x(0, 1) = 2;
   x(1, 0) = 3;
   x(1, 1) = 4;
 
   // Apply transformations
   auto x2 = x.Reshape({1, 4}).Squeeze();
   cout << x2 << endl;
 
   // Slice
   auto x3 = x.Reshape({2, 2}).Slice({{0, 2}, {0, 1}});
   cout << x3 << endl;
 
   // Create tensor as view on data without ownership
   float data[] = {5, 6, 7, 8};
   RTensor<float> y(data, {2, 2});
   cout << y << endl;
 
   // Create tensor as view on data with ownership
   auto data2 = std::make_shared<std::vector<float>>(4);
   float c = 9;
   for (auto &v : *data2) {
      v = c;
      c++;
   }
 
   RTensor<float> z(data2, {2, 2});
   cout << z << endl;
}

 
{ { 0, 0 } { 0, 0 } }
{ 1, 2, 3, 4 }
{ 1, 3 }
{ { 5, 6 } { 7, 8 } }
{ { 9, 10 } { 11, 12 } }

Date

December 2018

Author

Stefan Wunsch

Definition in file tmva001_RTensor.C.