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SvmFile.h

Go to the documentation of this file.

#ifndef Impala_Core_Training_SvmFile_h
#define Impala_Core_Training_SvmFile_h

#include "Link/Svm/LinkSvm.h"
#include "Basis/File.h"
#include <sstream>
#include <fstream>
#include "Util/ProgressPrinter.h"
#include "Link/Svm/LinkSvm.h"

namespace Impala
{
namespace Core
{
namespace Training
{

const double cInvalid = 666;

svm_problem* ReadSvmFile(const std::string& filename)
{
    ILOG_VAR(Impala.Core.Training.SvmFile);
    File f(filename, "r");
    if (!f.Valid())
        return 0;

    int sample=0;
    int nrNodes=0;
    while (!f.Eof())
    {
        std::istringstream iss(f.ReadLine(false));
        double label = cInvalid;
        iss >> label;
        if(label == cInvalid) // no label: empty line at the end of the file
            break;
        ++sample;
        while(!iss.eof())
        {
            int index;
            double value;
            char c = 0;
            iss >> index >> c >> value; // c should be ':'
            if(c != ':')
            {
                ILOG_ERROR("parse error in svm file "<< filename <<
                           "on line "<< sample);
                return 0;
            }
            ++nrNodes;
        }
        ++nrNodes; // extra node with index == -1
    }
    f.Rewind();

    // seccond pass:
    svm_problem* p = new svm_problem;
    p->l = sample;
    p->y = new double[sample];
    p->x = new svm_node*[sample];
    svm_node* nodes = new svm_node[nrNodes];
    svm_node* dst = nodes;
    for(int i=0 ; i<sample ; ++i)
    {
        std::istringstream iss(f.ReadLine(false));
        iss >> p->y[i];
        p->x[i] = dst;
        while(!iss.eof())
        {
            char c;
            iss >> dst->index >> c >> dst->value;
            ++dst;
        }
        dst->index = -1;
        ++dst;
    }
    f.Close();
    return p;
}

void WriteSvmFile(const svm_problem* p, const std::string& filename)
{
    ILOG_VAR(Impala.Core.Training.SvmFile);
    std::ofstream out(filename.c_str());
    if(!out.is_open())
    {
        ILOG_ERROR("could not open file " << filename);
        return;
    }
    for(int i=0 ; i<p->l ; ++i)
    {
        out << p->y[i];
        for(int j=0 ; p->x[i][j].index != -1 ; ++j)
            out << " " << p->x[i][j].index << ":" << p->x[i][j].value;
        out << "\n";
    }
    out.close();
}

}//namespace Core
}//namespace Training
}//namespace Impala

#endif

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