mary.my.id
small array utilities
feat: weightedIndex
author
Mary
date
(Mar 2, 2025, 9:48 AM +0700)
commit
1fd854b6
1fd854b68284b1649a30f6bd2625cef8b80d3ebb
parent
3d60c788
3d60c7889e1366f970a832e750dfadb46783d7e2
+34
+34
lib/mod.ts
+34
lib/mod.ts
···
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return result.reverse();
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};
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/**
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* randomly selects an index based on weights
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* @param weights array of weights (numbers)
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* @returns random index selected based on weight distribution or -1 if array is empty
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*/
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/*#__NO_SIDE_EFFECTS__*/
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export const weightedIndex = (weights: number[]): number => {
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const len = weights.length;
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const arr = new Array(len);
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let total = 0;
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for (let i = 0; i < len; i++) {
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const weight = Math.max(0, weights[i]);
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arr[i] = weight;
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total += weight;
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}
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if (total <= 0) {
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return -1;
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}
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let rand = Math.random() * total;
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for (let i = 0; i < len; i++) {
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rand -= arr[i];
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if (rand < 0) {
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return i;
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}
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}
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return len - 1;
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};