diginext-utils/dist/array/sample.js

README.md

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.sample = sample;
/**
 * Gets N random elements from an array.
 * If N is not specified or greater than array length, returns all elements shuffled.
 *
 * @template T - The type of elements in the array
 * @param array - The array to sample from
 * @param n - Number of elements to sample (optional)
 * @returns A new array with N random elements
 *
 * @example
 * ```ts
 * sample([1, 2, 3, 4, 5], 2); // Two random elements, e.g., [3, 1]
 * sample(['a', 'b', 'c']); // All elements in random order
 * sample([1, 2, 3], 5); // All elements in random order (n > length)
 * ```
 */
function sample(array, n) {
    if (!Array.isArray(array) || array.length === 0) {
        return [];
    }
    const sampleSize = n !== undefined ? Math.min(n, array.length) : array.length;
    if (sampleSize >= array.length) {
        // Return shuffled copy of entire array
        const result = [...array];
        for (let i = result.length - 1; i > 0; i--) {
            const j = Math.floor(Math.random() * (i + 1));
            const temp = result[i];
            result[i] = result[j];
            result[j] = temp;
        }
        return result;
    }
    // Use Set to avoid duplicates when sampling
    const result = [];
    const taken = new Set();
    const len = array.length;
    while (result.length < sampleSize) {
        const index = Math.floor(Math.random() * len);
        if (!taken.has(index)) {
            taken.add(index);
            const element = array[index];
            if (element !== undefined) {
                result.push(element);
            }
        }
    }
    return result;
}
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