我知道如何提取数组中的每个第 n 项,但我遇到的困难如下:
如何从 1800 个元素的数组中提取第 n 个项目,始终包括第一个和最后一个元素,总共最多 256 个元素?
Example:
array = [1,2,3,4,5,6,7,8,9,10];
提取5个元素:
extract = [1,3,5,7,10];
像这样?
/**
* Retrieve a fixed number of elements from an array, evenly distributed but
* always including the first and last elements.
*
* @param {Array} items - The array to operate on.
* @param {number} n - The number of elements to extract.
* @returns {Array}
*/
function distributedCopy(items, n) {
var elements = [items[0]];
var totalItems = items.length - 2;
var interval = Math.floor(totalItems/(n - 2));
for (var i = 1; i < n - 1; i++) {
elements.push(items[i * interval]);
}
elements.push(items[items.length - 1]);
return elements;
}
Example:
// Set up an array for testing purposes
var items = [];
for (var i=1; i<= 1800; i++) {
items.push(i);
}
var extracted = distributedCopy(items, 256);
console.log(extracted);
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