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CLK/Numeric/StringSimilarity.hpp

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//
// StringSimilarity.hpp
// Clock Signal
//
// Created by Thomas Harte on 21/05/2024.
// Copyright © 2024 Thomas Harte. All rights reserved.
//
#ifndef StringSimilarity_hpp
#define StringSimilarity_hpp
#include <cstdint>
#include <set>
#include <string>
namespace Numeric {
/// Seeks to implement algorithm as per http://www.catalysoft.com/articles/StrikeAMatch.html
///
/// @returns A number in the range 0.0 to 1.0 indicating the similarity between two strings;
/// 1.0 is most similar, 0.0 is least.
2024-05-24 19:39:38 +00:00
inline double similarity(std::string_view first, std::string_view second) {
if(first.size() < 2 || second.size() < 2) {
return 0.0;
}
const auto pairs = [](std::string_view source) -> std::set<uint16_t> {
std::set<uint16_t> result;
for(std::size_t c = 0; c < source.size() - 1; c++) {
if(isalpha(source[c]) && isalpha(source[c+1])) {
result.insert(static_cast<uint16_t>(
(toupper(source[c]) << 8) |
toupper(source[c+1])
));
}
}
return result;
};
const auto first_pairs = pairs(first);
const auto second_pairs = pairs(second);
const auto denominator = static_cast<double>(first_pairs.size() + second_pairs.size());
std::size_t numerator = 0;
auto first_it = first_pairs.begin();
auto second_it = second_pairs.begin();
while(first_it != first_pairs.end() && second_it != second_pairs.end()) {
if(*first_it == *second_it) {
++numerator;
++first_it;
++second_it;
} else if(*first_it < *second_it) {
++first_it;
} else {
++second_it;
}
}
return static_cast<double>(numerator * 2) / denominator;
}
}
#endif /* StringSimilarity_h */