|| || || || || || || ||

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MatFeatureNormalization.h

Go to the documentation of this file.

#ifndef Impala_Core_Matrix_MatFeatureNormalization_h
#define Impala_Core_Matrix_MatFeatureNormalization_h

#include "Core/Matrix/MatSet.h"

namespace Impala
{
namespace Core
{
namespace Matrix
{


template<class ArrayT>
inline void
MatFeatureNormalization(ArrayT* m)
{
    typedef typename ArrayT::ArithType ArithT;
    typedef typename ArrayT::StorType StorT;

    int nRow = MatNrRow(m);
    int nCol = MatNrCol(m);
    ArrayT* M = VecCreate<ArrayT>(nCol); //means
    ArrayT* S = VecCreate<ArrayT>(nCol); //variances 

    MatSet(M, 0);
    MatSet(S, 0);

    StorT* MPtr = VecE(M, 0);
    StorT* SPtr = VecE(S, 0);
    for (int i=0 ; i<nRow ; i++)
    {
        StorT* miPtr = MatE(m, i, 0);
        for (int j=0 ; j<nCol ; j++)
        {
            ArithT x = miPtr[j];
            MPtr[j] += x;
            SPtr[j] += x*x;
        }
    }

    for (int j=0 ; j<nCol ; j++)
    {
        ArithT mj = MPtr[j]/nRow;
        SPtr[j] = sqrt( SPtr[j]/nRow - mj * mj );
    }

    //normalize
    for (int k=0 ; k<nRow; k++)
    {
        StorT* mkPtr = MatE(m, k, 0);
        for (int j=0 ; j<nCol ; j++)
            mkPtr[j] = mkPtr[j] / SPtr[j];
    }

    delete M;
    delete S;
}

} // namespace Matrix
} // namespace Core
} // namespace Impala

#endif

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