I'm looking for an array method implementation named Array.window(n) that invoked on an array with parameter n, would give a contiguous overlapping array slice.
Example:
let a = [1, 2, 3, 4, 5, 6]
a.window(2) // [[1, 2], [2, 3], [3, 4], [4, 5], [5, 6]]
a.window(3) // [[1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6]]
a.window(4) // [[1, 2, 3, 4], [2, 3, 4, 5], [3, 4, 5, 6]]
a.window(10)// []
How can I accomplish this?
Here you go with a slightly shorter example using array functions:
let a = [1, 2, 3, 4, 5, 6];
function windowedSlice(arr, size) {
let result = [];
arr.some((el, i) => {
if (i + size > arr.length) return true;
result.push(arr.slice(i, i + size));
});
return result;
}
console.log(windowedSlice(a, 2));
console.log(windowedSlice(a, 3));
console.log(windowedSlice(a, 4));
console.log(windowedSlice(a, 5));
if (i + size > arr.length)I think this would suffice:
function arrayWindow(array, n) {
if (array.length < n || n <= 0) {
return []
}
let arrayLength = array.length
let result = []
for (let i = 0; i < arrayLength; i++) {
let slicedArray = array.slice(i, n+i)
if (slicedArray && slicedArray.length === n) {
result.push(slicedArray)
continue
}
break
}
return result
}
let arr = [1, 2, 3, 4, 5, 6]
console.log(arrayWindow(arr, 2))
console.log(arrayWindow(arr, 3))
console.log(arrayWindow(arr, 4))
console.log(arrayWindow(arr, 5))
console.log(arrayWindow(arr, 10))
console.log(arrayWindow(arr, 0))Here is a simple rolling window function. Notice that we can determine the number of iterations based on array length minus the desired window size.
/**
* Produces a rolling window of desired length {w} on a 1d array.
*
* @param {Array} a The 1d array to window.
* @param {Number} w The desired window size.
* @return {Array} A multi-dimensional array of windowed values.
*/
function rolling(a, w) {
let n = a.length;
let result = [];
if (n < w || w <= 0) {
return result;
}
for (let i = 0; i < n - w + 1; i++) {
result.push(a.slice(i, w + i));
}
return result;
}
let a = [1, 2, 3, 4, 5];
console.log(JSON.stringify(rolling(a, 3)));
