locutus/clojure/core/partition.js

Locutus other languages' standard libraries to JavaScript for fun and educational purposes

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.partition = partition;
function partition(n, values, step = n, pad = null) {
    //      discuss at: https://locutus.io/clojure/partition/
    // parity verified: Clojure 1.12
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //          note 1: Mirrors Clojure partition for n/step/pad forms, dropping incomplete trailing partitions unless pad completes them.
    //       example 1: partition(3, [1, 2, 3, 4, 5])
    //       returns 1: [[1, 2, 3]]
    //       example 2: partition(3, [1, 2, 3, 4, 5], 1)
    //       returns 2: [[1, 2, 3], [2, 3, 4], [3, 4, 5]]
    //       example 3: partition(3, [1, 2, 3, 4, 5], 3, ['x', 'y'])
    //       returns 3: [[1, 2, 3], [4, 5, 'x']]
    if (!Array.isArray(values)) {
        return [];
    }
    const size = Math.trunc(Number(n));
    const stride = Math.trunc(Number(step));
    if (!Number.isFinite(size) || size <= 0) {
        throw new RangeError('partition(): n must be a positive integer');
    }
    if (!Number.isFinite(stride) || stride <= 0) {
        throw new RangeError('partition(): step must be a positive integer');
    }
    const out = [];
    for (let i = 0; i < values.length; i += stride) {
        const chunk = values.slice(i, i + size);
        if (chunk.length === size) {
            out.push(chunk);
            continue;
        }
        if (!pad || chunk.length === 0) {
            continue;
        }
        const needed = size - chunk.length;
        if (pad.length >= needed) {
            out.push([...chunk, ...pad.slice(0, needed)]);
        }
    }
    return out;
}