遍历2d Typescript数组并根据索引处的值创建新数组 [英] Looping through 2d Typescript array and making new array from value at index

问题描述

我在打字稿中有以下数组：

I have the following array in Typescript:

this.days_in_month = [
    [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31], 
    [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31], 
    [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31], 
    [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31], 
];

我想遍历它，并为每个值创建一个新的，长度为的空数组

I want to loop through it, and for every value create a new, empty, array of length of that value and add that array to another array of arrays.

例如：第一个值是31，所以我将创建一个31东西长的空数组并添加31数组到一个数组的数组。下一个值为28，因此我将创建一个长度为28的数组，然后将28数组添加到数组数组中，使其现在包含31数组和28数组。

Eg: the first value is 31 so I would create an empty array 31 things long and add the 31-array to an array of arrays. The next value is 28 so I would then create an array 28 things long and then add the 28-array to the array of arrays so that it now contains the 31-array and the 28-array.

在Python中，我会使用range，但是我不确定如何在Typescript中执行此操作。

In Python I would use range, but I'm not sure how to do this in Typescript.

到目前为止，我有以下问题：

So far I have the following ts:

this.days_in_month.forEach(function(value, index, array) {
    console.log(value, index, array);
    no_of_days: number = this.days_in_month(value);
    let days = new Array<number>(no_of_days);
})

推荐答案

您可以使用 Array.prototype.map ：

let result = days_in_month.map(
    year => year.map(
        (days) => new Array(days)
    )
);

请记住，创建的数组具有未定义的值。通常，您将生成所需的数组值，而不是仅为每个月初始化一个空数组。

Bear in mind, the created arrays have undefined values. You would typically generate the required values of the array instead of just initializing an empty array for each month.

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