加入前两个元素并创建新数组？答案

【问题标题】：Join first two elements and create new array?加入前两个元素并创建新数组？
【发布时间】：2018-08-18 10:57:12
【问题描述】：

在玩了几个小时join() 和slice() 函数之后，我发现你不能在复杂数组上使用这两个函数。所以我来这里寻求帮助。

我正在尝试获取以下数据：

 var data = [
            ["North", "Tennis",37, 25, 11, 9, 42, 13],
            ["East", "Football", 41, 2, 3, 26, 47, 21],
            ["South", "Rugby", 7, 22, 35, 45, 11, 46],
            ["West", "Rugby", 30, 21, 44, 23, 4, 47],
            ["North East", "Football", 35, 27, 12, 39, 34, 13],
            ["North West", "Football", 23, 4, 41, 35, 9, 47]
        ];

看起来像这样（输出）：

var result = [
    ["North: Tennis", 37, 25, 11, 9, 42, 13],
    ["East: Football", 41, 2, 3, 26, 47, 21],
    ["South: Rugby", 7, 22, 35, 45, 11, 46],
    ["West: Rugby", 30, 21, 44, 23, 4, 47],
    ["North East: Football", 35, 27, 12, 39, 34, 13],
    ["North West: Football", 23, 4, 41, 35, 9, 47]
];

任何帮助将不胜感激

【问题讨论】：

你想把你的数组转换成一个对象吗？
@MohammadUsman 一点也不，我的其余代码将使用数组。我只想重新格式化它，并在第一个索引之后附加一个冒号并删除逗号
所以你想得到一个字符串作为输出？还是字符串数组？或者前两个元素由 : 连接的数组？还是……？
一个数组数组，其中第一个元素由:连接

标签： javascript arrays multidimensional-array

【解决方案1】：

当您想将一个数组转换为另一个数组时，将原始数组.map 转换为另一个数组是有意义的，方法是获取每个子数组的前两个元素并将它们连接在一起，然后通过添加其余元素来构建一个新子数组将元素（我们在数组解构过程中使用 rest 参数获得）复制到包含连接字符串的新数组。

let data = [
  ["North", "Tennis",37, 25, 11, 9, 42, 13],
  ["East", "Football", 41, 2, 3, 26, 47, 21],
  ["South", "Rugby", 7, 22, 35, 45, 11, 46],
  ["West", "Rugby", 30, 21, 44, 23, 4, 47],
  ["North East", "Football", 35, 27, 12, 39, 34, 13],
  ["North West", "Football", 23, 4, 41, 35, 9, 47]
];

let result = data.map(([s1, s2, ...rest]) => [`${s1}: ${s2}`, ...rest]);

console.log(result);

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参考资料：

【讨论】：

【解决方案2】：

如果我正确理解您的问题，您正在寻找以下输出。我已经使用 JavaScript 的 .map() 函数稍微重构了数据。 More information on .map here.

var data = [
  ["North", "Tennis", 37, 25, 11, 9, 42, 13],
  ["East", "Football", 41, 2, 3, 26, 47, 21],
  ["South", "Rugby", 7, 22, 35, 45, 11, 46],
  ["West", "Rugby", 30, 21, 44, 23, 4, 47],
  ["North East", "Football", 35, 27, 12, 39, 34, 13],
  ["North West", "Football", 23, 4, 41, 35, 9, 47]
];

const formattedData = data.map(row => {

  return [
    [row[0] + ': ' + row[1]],
    row[2],
    row[3],
    row[4],
    row[5],
    row[6],
    row[7]
  ];
});

console.log(formattedData);

【讨论】：

【解决方案3】：

我会写你的代码。

var data = [
  ["North", "Tennis", 37, 25, 11, 9, 42, 13],
  ["East", "Football", 41, 2, 3, 26, 47, 21],
  ["South", "Rugby", 7, 22, 35, 45, 11, 46],
  ["West", "Rugby", 30, 21, 44, 23, 4, 47],
  ["North East", "Football", 35, 27, 12, 39, 34, 13],
  ["North West", "Football", 23, 4, 41, 35, 9, 47]
];

// Final resulting array is created by concatenating the first and
// second index elements of each inner array of data. The rest data
// is being copied as it is using slice and spread operator.
const result = data.reduce(
  (mem, cur) => [...mem, [`${cur[0]}: ${cur[1]}`, ...cur.slice(2)]],
  []
);

console.log(result);

【讨论】：

IMO：reduce 在这里使事情过于复杂，为什么不只是 map 呢？我投反对票的原因：我会编写你的代码。不是对正在发生的事情的描述。
@JonasWilms 这里没有什么好解释的，每一行都是自我解释的。要我解释每一行吗？我在这里只使用了一种方法.reduce。我应该对reduce 解释什么？
@JonasWilms 你从You can use .map() and some array destructuring...那里得到了什么解释？没什么..但我对这条线没意见..
@JonasWilms 这不是一个解释。它被提到是为了让像你这样快乐的人......我跳过了。我不打扰无缘无故争论的人..
@JonasWilms 什么样的答案is this mate ？您是否在这里付出了任何努力来解释而不是编写代码本身？先让自己变得像样，然后评论别人..也就是说，我将不再在这里发表评论..我只是试着忽略废话..

【解决方案4】：

您可以使用map 方法。它需要一个为每个元素执行的回调。然后它返回一个 new 数组，其中包含每个索引中的新数据。例如：

var data = [
            ["North", "Tennis",37, 25, 11, 9, 42, 13],
            ["East", "Football", 41, 2, 3, 26, 47, 21],
            ["South", "Rugby", 7, 22, 35, 45, 11, 46],
            ["West", "Rugby", 30, 21, 44, 23, 4, 47],
            ["North East", "Football", 35, 27, 12, 39, 34, 13],
            ["North West", "Football", 23, 4, 41, 35, 9, 47]
        ];
        
        
newData = data.map((el, i, arr) => {
  el[0] = `${el[0]}: ${el[1]}`   // reassinging el[0]
  el.splice(1, 1);               // removing 2 array element
 });

【讨论】：