Created
April 18, 2024 23:27
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Lightweight module to pick a random element from a weighted array
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class Picker { | |
/** | |
* @param {Function} [randomFn] Random number generator | |
*/ | |
constructor(randomFn = Math.random) { | |
this.random = randomFn; | |
} | |
/** | |
* Pick a random value based on its weight. | |
* @param {Array} data Array of values. | |
* @return {Mixed} | |
*/ | |
pick(data) { | |
if (!Array.isArray(data) || data.length === 0) { | |
throw new TypeError('Expected a non-empty Array as the first argument'); | |
} | |
const totalWeight = data.reduce((sum, item) => sum + item[1], 0); | |
const rand = this.random() * totalWeight; | |
let weightSum = 0; | |
for (const [value, weight] of data) { | |
weightSum += weight; | |
if (rand <= weightSum) { | |
return value; | |
} | |
} | |
// Fallback in case of unexpected error | |
return data[data.length - 1][0]; | |
} | |
} | |
const pick = (data, randomFn) => { | |
const picker = new Picker(randomFn); | |
return picker.pick(data); | |
}; | |
export default pick; | |
export { pick, Picker }; |
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