ProcMultiply.cc

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// -*- C++ -*-
//
// Package:     MVAComputer
// Class  :     
// 

// Implementation:
//     Multiplies n input variables to produce one output variable.
//
// Author:      Christophe Saout
// Created:     Sat Apr 24 15:18 CEST 2007
//

#include <cstdlib>
#include <algorithm>
#include <iterator>
#include <vector>

#include "FWCore/Utilities/interface/Exception.h"

#include "PhysicsTools/MVAComputer/interface/VarProcessor.h"
#include "PhysicsTools/MVAComputer/interface/Calibration.h"

using namespace PhysicsTools;

namespace { // anonymous

class ProcMultiply : public VarProcessor {
    public:
    typedef VarProcessor::Registry::Registry<ProcMultiply,
                    Calibration::ProcMultiply> Registry;

    ProcMultiply(const char *name,
               const Calibration::ProcMultiply *calib,
               const MVAComputer *computer);
    ~ProcMultiply() override {}

    void configure(ConfIterator iter, unsigned int n) override;
    void eval(ValueIterator iter, unsigned int n) const override;
    std::vector<double> deriv(
                ValueIterator iter, unsigned int n) const override;

    private:
    typedef std::vector<unsigned int>   Config;

    unsigned int                in;
    std::vector<Config>         out;
};

ProcMultiply::Registry registry("ProcMultiply");

ProcMultiply::ProcMultiply(const char *name,
                       const Calibration::ProcMultiply *calib,
                       const MVAComputer *computer) :
    VarProcessor(name, calib, computer),
    in(calib->in)
{
    std::copy(calib->out.begin(), calib->out.end(),
              std::back_inserter(out));
}

void ProcMultiply::configure(ConfIterator iter, unsigned int n)
{
    if (in != n)
        return;

    for(unsigned int i = 0; i < in; i++)
        iter++(Variable::FLAG_NONE);

    for(unsigned int i = 0; i < out.size(); i++)
        iter << Variable::FLAG_NONE;
}

void ProcMultiply::eval(ValueIterator iter, unsigned int n) const
{
    double *values = (double*)alloca(in * sizeof(double));
    for(double *pos = values; iter; iter++, pos++) {
        if (iter.size() != 1)
            throw cms::Exception("ProcMultiply")
                << "Special input variable encountered "
                   "at index " << (pos - values) << "."
                << std::endl;
        *pos = *iter;
    }

    for(std::vector<Config>::const_iterator config = out.begin();
        config != out.end(); ++config) {
        double product = 1.0;
        for(std::vector<unsigned int>::const_iterator var =
                            config->begin();
            var != config->end(); var++)
            product *= values[*var];

        iter(product);
    }
}

std::vector<double> ProcMultiply::deriv(
                ValueIterator iter, unsigned int n) const
{
    std::vector<double> values;
    std::vector<unsigned int> offsets;
    unsigned int size = 0;
    while(iter) {
        offsets.push_back(size);
        size += iter.size();
        values.push_back(*iter++);
    }

    std::vector<double> result(out.size() * size, 0.0);
    unsigned int k = 0;
    for(std::vector<Config>::const_iterator config = out.begin();
        config != out.end(); ++config, k++) {
        for(unsigned int i = 0; i < config->size(); i++) {
            double product = 1.0;
            for(unsigned int j = 0; j < config->size(); j++)
                if (i != j)
                    product *= values[(*config)[j]];

            result[k * size + offsets[i]] = product;
        }
    }

    return result;
}

} // anonymous namespace