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87 lines
2.4 KiB
TypeScript
87 lines
2.4 KiB
TypeScript
// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
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// This module is browser compatible.
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/** Options for {@linkcode slidingWindows}. */
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export interface SlidingWindowsOptions {
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/**
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* If step is set, each window will start that many elements after the last
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* window's start.
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*
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* @default {1}
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*/
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step?: number;
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/**
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* If partial is set, windows will be generated for the last elements of the
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* collection, resulting in some undefined values if size is greater than 1.
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*
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* @default {false}
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*/
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partial?: boolean;
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}
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/**
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* Generates sliding views of the given array of the given size and returns a
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* new array containing all of them.
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*
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* If step is set, each window will start that many elements after the last
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* window's start. (Default: 1)
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*
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* If partial is set, windows will be generated for the last elements of the
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* collection, resulting in some undefined values if size is greater than 1.
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*
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* @typeParam T The type of the array elements.
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*
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* @param array The array to generate sliding windows from.
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* @param size The size of the sliding windows.
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* @param options The options for generating sliding windows.
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*
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* @returns A new array containing all sliding windows of the given size.
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*
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* @example Usage
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* ```ts
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* import { slidingWindows } from "@std/collections/sliding-windows";
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* import { assertEquals } from "@std/assert";
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* const numbers = [1, 2, 3, 4, 5];
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*
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* const windows = slidingWindows(numbers, 3);
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* assertEquals(windows, [
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* [1, 2, 3],
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* [2, 3, 4],
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* [3, 4, 5],
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* ]);
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*
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* const windowsWithStep = slidingWindows(numbers, 3, { step: 2 });
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* assertEquals(windowsWithStep, [
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* [1, 2, 3],
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* [3, 4, 5],
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* ]);
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*
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* const windowsWithPartial = slidingWindows(numbers, 3, { partial: true });
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* assertEquals(windowsWithPartial, [
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* [1, 2, 3],
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* [2, 3, 4],
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* [3, 4, 5],
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* [4, 5],
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* [5],
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* ]);
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* ```
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*/
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export function slidingWindows<T>(
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array: readonly T[],
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size: number,
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options: SlidingWindowsOptions = {},
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): T[][] {
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const { step = 1, partial = false } = options;
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if (
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!Number.isInteger(size) || !Number.isInteger(step) || size <= 0 || step <= 0
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) {
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throw new RangeError("Both size and step must be positive integer.");
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}
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return Array.from(
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{ length: Math.floor((array.length - (partial ? 1 : size)) / step + 1) },
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(_, i) => array.slice(i * step, i * step + size),
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);
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}
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