locutus/esm/kotlin/collections/windowed.js

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

export function windowed(values, size, step = 1, partialWindows = false) {
    //  discuss at: https://locutus.io/kotlin/collections/windowed/
    // original by: Kevin van Zonneveld (https://kvz.io)
    //      note 1: Produces sliding windows over values, similar to Kotlin's windowed(size, step, partialWindows).
    //   example 1: windowed([1, 2, 3, 4, 5], 3)
    //   returns 1: [[1, 2, 3], [2, 3, 4], [3, 4, 5]]
    //   example 2: windowed([1, 2, 3, 4, 5], 3, 2)
    //   returns 2: [[1, 2, 3], [3, 4, 5]]
    //   example 3: windowed([1, 2, 3, 4, 5], 3, 2, true)
    //   returns 3: [[1, 2, 3], [3, 4, 5], [5]]
    if (!Array.isArray(values)) {
        return [];
    }
    const width = Math.trunc(Number(size));
    const stride = Math.trunc(Number(step));
    if (!Number.isFinite(width) || width <= 0) {
        throw new RangeError('windowed(): size must be a positive integer');
    }
    if (!Number.isFinite(stride) || stride <= 0) {
        throw new RangeError('windowed(): step must be a positive integer');
    }
    const out = [];
    for (let i = 0; i < values.length; i += stride) {
        const window = values.slice(i, i + width);
        if (window.length === width || (partialWindows && window.length > 0)) {
            out.push(window);
        }
    }
    return out;
}