sampling.cpp

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/*
 *  sampling.cpp - statistical sampling functions
 *  Copyright (C) 2015, D Haley 

 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.

 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.

 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "atomprobe/helper/aptAssert.h"

#include "atomprobe/helper/sampling.h"

#include "gsl/gsl_randist.h"


namespace AtomProbe 
{

using std::vector;
void sampleIons(const vector<IonHit> &ions, float sampleFactor, 
            vector<IonHit> &sampled, bool strongRandom)
{
    //obtain library random number generator, if we will use it
    // otherwise, sampling function will use its own weak generator
    gsl_rng *r;
    if(strongRandom)
        r=randGen.getRng();
    else
        r=0;

    size_t nSamples =sampleFactor*ions.size(); 
    sampled.resize(nSamples);
    randomSelect(sampled,ions,nSamples,r);
}

#ifdef DEBUG
bool testSampling()
{
    vector<IonHit> ions,sampled;
    IonHit h(Point3D(1.0f,2.0f,3.0f),1.0f);
    for(unsigned int ui=0;ui<10;ui++)
        ions.push_back(h);

    sampleIons(ions,0.5,sampled);

    TEST(sampled.size() == 5,"sample count");
    for(unsigned int ui=0;ui<sampled.size();ui++)
    {
        TEST(sampled[ui] == h,"sampled data integrity");
    }


    //Try again with strong randomsiation
    sampled.clear();
    sampleIons(ions,0.5,sampled,true);
    TEST(sampled.size() == 5,"sample count");
    for(unsigned int ui=0;ui<sampled.size();ui++)
    {
        TEST(sampled[ui] == h,"sampled data integrity");
    }

    return true;
}
#endif

}