binary_distance.hpp

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/*
Copyright© 2014 Akihiro Nishimura

This software is released under the MIT License.
http://opensource.org/licenses/mit-license.php
*/

#ifndef SIG_UTIL_BINARY_DISTANCE_HPP
#define SIG_UTIL_BINARY_DISTANCE_HPP

#include "comparable_check.hpp"

namespace sig
{

struct BinaryDistance
{
    template <class C1, class C2,
        typename = typename std::enable_if<std::is_integral<typename impl::container_traits<C1>::value_type>::value>::type,
        typename = typename std::enable_if<std::is_integral<typename impl::container_traits<C2>::value_type>::value>::type
    >
    double operator()(C1 const& vec1, C2 const& vec2) const
    {
        assert(is_comparable(vec1, vec2, impl::NumericVectorTag()));

        int ether = 0, both = 0;
        auto it1 = std::begin(vec1), end1 = std::end(vec1);
        auto it2 = std::begin(vec2), end2 = std::end(vec2);

        for (; it1 != end1 && it2 != end2; ++it1, ++it2){
            if (*it1 == 1 && *it2 == 1) ++both;
            else if (*it1 == 1 || *it2 == 1) ++ether;
        }
        return static_cast<double>(ether) / (ether + both);
    }
};


const BinaryDistance binary_distance;

}
#endif