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-rw-r--r--utils/match-util.js154
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diff --git a/utils/match-util.js b/utils/match-util.js
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-/**
- * match utility;
- * includes fuzzy and partial match functions too;
- * many of them return a match-rate
- */
-
-
-// fuzzy match
-////////////////////////////////////////////////////////////////////////////////
-
-/** Ngram fuzzy match algorithm
- * (simple and fast)
- */
-const createNgram = (word, n) => { // Ngram creation
- if (word.length <3) return word;
- const vector = [];
- for (let i = 0; i < word.length-n+1; ++i) {
- vector.push(word.slice(i, i + n));
- }
- return vector;
-};
-
-/** similarity
- * rates similarity between 2 words
- * based on Ngram matches of N = n letters;
- * implements a 2-dim check (all a-Ngrams vs all all b-Ngrams)
- *
- * @param {string} a : first word
- * @param {string} b : second word
- * @param {int} n : Ngram base
- * @returns {float} : match percentage as a float in [0, 1]
- */
-const similarity = (a, b, n) => { // Ngram match score
- if (a.length > 0 && b.length > 0) {
- const aNgram = createNgram(a, n);
- const bNgram = createNgram(b, n);
- let hits = 0;
- for (let x = 0; x < aNgram.length; ++x) {
- for (let y = 0; y < bNgram.length; ++y) {
- if (aNgram[x] === bNgram[y]) {
- hits += 1;
- }
- }
- }
- if (hits > 0) {
- const union = aNgram.length + bNgram.length;
- return (2.0 * hits) / union;
- }
- }
- return 0;
-};
-
-/** resemblance
- * is an alternative similarity rating;
- * implements an 1-dim Ngram similarity check
- * and it's much faster than similarity()
- */
-const resemblance = (a, b, n) => {
- if (a.length > n && b.length >= a.length) {
- const aNgram = createNgram(a, n);
- let hits = 0;
- for (let i = 0; i < aNgram.length; ++i) {
- if (b.includes(aNgram[i])) {
- hits++;
- }
- }
- if (hits > 0) {
- // rate resemblance based on hits and length-similarity
- return (hits / aNgram.length) * (a.length / b.length);
- }
- }
- return 0;
-}
-
-
-// exact and partial match
-////////////////////////////////////////////////////////////////////////////////
-
-/** is_exact_match
- * check if a searching string -> query (string/latin in kb-format)
- * matches exactly an item of the array of synonyms -> chkArr (array of utf-8/strings)
- *
- * @param {string} query: searching string; string/latin in kb-format
- * @param {array} chkArr: array of synonyms; (array of utf-8/strings)
- * @return {boolean}: true|false
- */
-function exact( query, chkArr ) {
- found = false;
- chkArr.forEach( w => { if (w == query) found = true });
- return found;
-}
-
-function partial( query, chkArr ) {
- found = false;
- chkArr.forEach( w => { if (w.includes(query)) found = true });
- return found;
-}
-
-/** is exact match + weight rating
- * @returns {float} weight rates depth of array when a match is found
- */
-function weighted_exact( query, chkArr ) {
- let weight = 0; // closer to left/begin rating
- let len = chkArr.length;
- for(let i = 0; i < len ; i++) { // i ~ depth
- if (chkArr[i] == query) {
- // weights array depth
- weight = (len - i + 1.0) / len;
- break;
- }
- }
- return weight;
-}
-
-
-/** is partial match + weight rating
- *
- * @param query (string): searching string; string/latin in kb-format
- * @param chkArr (array): array of synonyms; (array of utf-8/strings)
- * @returns {float} weight rates both match position and depth of match
- *
- * (*) optimization NOTE:
- * Given the weight `W` and the depth `i`,
- * the best weight for next `i` shall be: `(L - (i+1)) / L`
- * To be imposibbe to have a better weight, should:
- * W > (L - (i+1)) / L => ... => i > (L - L*W - 1)
- */
-function weighted_partial( query, chkArr ) {
- let rate = 0;
- let weight = 0;
- let len = chkArr.length;
- for( let i = 0 ; i < len ; i++ ) {
- let chk = chkArr[i].indexOf(query)
- if (chk != -1) {
- rate = (len - i) / (len + 2.0 * chk);
- weight = rate > weight ? rate : weight;
- }
- if (i > (len - len * weight - 1)) {
- break; // better rating is not possible (*)
- }
- }
- return weight;
-}
-
-
-// exports
-module.exports = {
- exact,
- partial,
- weighted_exact,
- weighted_partial,
- similarity,
- resemblance
-}