compute_scale.hpp

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#ifndef MUMOSA_COMPUTE_SCALE_HPP
#define MUMOSA_COMPUTE_SCALE_HPP
 
#include <limits>
#include <utility>
#include <vector>
 
#include "sanisizer/sanisizer.hpp"
 
namespace mumosa {
 
template<typename Distance_>
Distance_ compute_scale(const std::pair<Distance_, Distance_>& ref, const std::pair<Distance_, Distance_>& target) {
    if (target.first == 0 || ref.first == 0) {
        if (target.second == 0) {
            return std::numeric_limits<Distance_>::infinity();
        } else if (ref.second == 0) {
            return 0;
        } else {
            return ref.second / target.second; 
        }
    } else {
        return ref.first / target.first;
    }
}
 
template<typename Distance_>
std::vector<Distance_> compute_scale(const std::vector<std::pair<Distance_, Distance_> >& distances) {
    const auto ndist = distances.size();
    auto output = sanisizer::create<std::vector<Distance_> >(ndist);
 
    // Use the first entry with a non-zero RMSD as the reference.
    bool found_ref = false;
    I<decltype(ndist)> ref = 0;
    for (I<decltype(ndist)> e = 0; e < ndist; ++e) {
        if (distances[e].second) {
            found_ref = true;
            ref = e;
            break;
        }
    }
 
    // If all of them have a zero RMSD, then all scalings are zero, because it doesn't matter.
    if (found_ref) {
        const auto& dref = distances[ref];
        for (I<decltype(ndist)> e = 0; e < ndist; ++e) {
            output[e] = (e == ref ? static_cast<Distance_>(1) : compute_scale(dref, distances[e]));
        }
    }
 
    return output;
}
 
}
 
#endif