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Similarity calculator for string inputs implemented in TypeScript
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| /** | |
| * Get the similarity percentage between two strings. | |
| * Based on {@link https://gist.github.com/sumn2u/0e0b5d9505ad096284928a987ace13fb#file-jaro-wrinker-js} | |
| */ | |
| export function calculateStringsSimilarity( | |
| firstString: string, | |
| secondString: string, | |
| config?: { | |
| /** | |
| * If true, the function will return the similarity percentage as a float number between 0 and 1. | |
| * If false, the function will return the similarity percentage as an float between 0 and 100. | |
| */ | |
| asRatio?: boolean | |
| }, | |
| ) { | |
| if (firstString.trim() === secondString.trim()) | |
| return config?.asRatio ? 1 : 100 | |
| let matchesFound = 0 | |
| const range = | |
| Math.floor(Math.max(firstString.length, secondString.length) / 2) - 1 | |
| const matchesInFirstString = Array.from({ length: firstString.length }) | |
| const matchesInSecondString = Array.from({ length: secondString.length }) | |
| for ( | |
| let firstStringCharIndex = 0; | |
| firstStringCharIndex < firstString.length; | |
| ++firstStringCharIndex | |
| ) { | |
| const high = | |
| firstStringCharIndex + range <= secondString.length | |
| ? firstStringCharIndex + range | |
| : secondString.length - 1 | |
| let low = firstStringCharIndex >= range ? firstStringCharIndex - range : 0 | |
| while (low <= high) { | |
| if ( | |
| !matchesInFirstString[firstStringCharIndex] && | |
| !matchesInSecondString[low] && | |
| firstString.charAt(firstStringCharIndex) === secondString.charAt(low) | |
| ) { | |
| ++matchesFound | |
| matchesInFirstString[firstStringCharIndex] = matchesInSecondString[ | |
| low | |
| ] = true | |
| low = high | |
| } | |
| low++ | |
| } | |
| } | |
| if (matchesFound === 0) return 0 | |
| let transpositionsCounterIndex = 0 | |
| let transpositions = 0 | |
| for ( | |
| let firstStringCharIndex = 0; | |
| firstStringCharIndex < firstString.length; | |
| ++firstStringCharIndex | |
| ) { | |
| if (matchesInFirstString[firstStringCharIndex]) | |
| while (transpositionsCounterIndex < secondString.length) { | |
| if (matchesInSecondString[transpositionsCounterIndex]) { | |
| transpositionsCounterIndex += 1 | |
| break | |
| } | |
| if ( | |
| firstString.charAt(firstStringCharIndex) !== | |
| secondString.charAt(transpositionsCounterIndex) | |
| ) | |
| ++transpositions | |
| transpositionsCounterIndex++ | |
| } | |
| } | |
| let weight = | |
| (matchesFound / firstString.length + | |
| matchesFound / secondString.length + | |
| (matchesFound - transpositions / 2) / matchesFound) / | |
| 3 | |
| let lengthPrefix = 0 | |
| const scoreScalingFactor = 0.1 | |
| if (weight > 0.7) { | |
| while ( | |
| firstString[lengthPrefix] === secondString[lengthPrefix] && | |
| lengthPrefix < 4 | |
| ) | |
| ++lengthPrefix | |
| weight = weight + lengthPrefix * scoreScalingFactor * (1 - weight) | |
| } | |
| if (config?.asRatio) return weight | |
| return weight * 100 | |
| } |
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