85 lines
2.5 KiB
JavaScript
85 lines
2.5 KiB
JavaScript
module.exports = {
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compareTwoStrings,
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findBestMatch
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};
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function compareTwoStrings(first, second) {
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first = first.replace(/\s+/g, '')
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second = second.replace(/\s+/g, '')
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if (!first.length && !second.length) return 1; // if both are empty strings
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if (!first.length || !second.length) return 0; // if only one is empty string
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if (first === second) return 1; // identical
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if (first.length === 1 && second.length === 1) return 0; // both are 1-letter strings
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if (first.length < 2 || second.length < 2) return 0; // if either is a 1-letter string
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let firstBigrams = new Map();
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for (let i = 0; i < first.length - 1; i++) {
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const bigram = first.substr(i, 2);
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const count = firstBigrams.has(bigram)
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? firstBigrams.get(bigram) + 1
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: 1;
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firstBigrams.set(bigram, count);
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};
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let intersectionSize = 0;
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for (let i = 0; i < second.length - 1; i++) {
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const bigram = second.substr(i, 2);
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const count = firstBigrams.has(bigram)
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? firstBigrams.get(bigram)
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: 0;
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if (count > 0) {
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firstBigrams.set(bigram, count - 1);
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intersectionSize++;
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}
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}
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return (2.0 * intersectionSize) / (first.length + second.length - 2);
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}
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function findBestMatch(mainString, targetStrings) {
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if (!areArgsValid(mainString, targetStrings)) throw new Error('Bad arguments: First argument should be a string, second should be an array of strings');
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const ratings = [];
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let bestMatchIndex = 0;
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for (let i = 0; i < targetStrings.length; i++) {
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const currentTargetString = targetStrings[i];
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const currentRating = compareTwoStrings(mainString, currentTargetString)
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ratings.push({target: currentTargetString, rating: currentRating})
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if (currentRating > ratings[bestMatchIndex].rating) {
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bestMatchIndex = i
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}
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}
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const bestMatch = ratings[bestMatchIndex]
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return { ratings, bestMatch, bestMatchIndex };
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}
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function flattenDeep(arr) {
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return Array.isArray(arr) ? arr.reduce((a, b) => a.concat(flattenDeep(b)), []) : [arr];
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}
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function areArgsValid(mainString, targetStrings) {
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if (typeof mainString !== 'string') return false;
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if (!Array.isArray(targetStrings)) return false;
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if (!targetStrings.length) return false;
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if (targetStrings.find(s => typeof s !== 'string')) return false;
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return true;
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}
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function letterPairs(str) {
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const pairs = [];
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for (let i = 0, max = str.length - 1; i < max; i++) pairs[i] = str.substring(i, i + 2);
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return pairs;
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}
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function wordLetterPairs(str) {
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const pairs = str.toUpperCase().split(' ').map(letterPairs);
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return flattenDeep(pairs);
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}
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