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