從三個陣列中獲取第一個元素并將它們放入自己的陣列中，然后在javascript中對第二個元素執行相同操作，依此類推

我有三個陣列

arr1 = ["a1", "a2", "a3"]

arr2 = ["b1", "b2", "b3"]

arr3 = ["c1", "c2", "c3"]

我希望三個新陣列看起來像這樣

arr4 = ["a1", "b1", "c1"]

arr5 = ["a2", "b2", "c2"]

arr6 = ["a3", "b3", "c3"]

如何在 JavaScript 中完成獲取這些新陣列？

uj5u.com熱心網友回復：

這是一種方法 - 將源陣列放在一個變數中，使用最短源陣列的長度作為迭代器長度并動態創建新變數。

let arr1 = ["a1", "a2", "a3"]
let arr2 = ["b1", "b2", "b3"]
let arr3 = ["c1", "c2", "c3"]

// just in case they're not all the same length, we'll use the shortest one as the iterator length

let ct = 0,
  st = 4,
  arrs = [arr1, arr2, arr3],
  len = Math.min(arr1.length, arr2.length, arr3.length);
while (ct < len) {
  this[`arr${st ct}`] = arrs.map(a => a[ct]);
  ct  ;
}

console.log(arr5)

uj5u.com熱心網友回復：

let mixedArr = [arr1, arr2, arr3];
let res = [];
for (i=0;i<mixedArr.length;i  ) {
    res.push(mixedArr.map(arr => arr[i]))
}
console.log(res)

然后你可以從完成的陣列中獲取你需要的東西

uj5u.com熱心網友回復：

您可以使用兩個回圈來執行此操作，但您將在一個陣列中添加所有陣列以執行回圈，我們在另一個陣列中提取新陣列

這是你的代碼

let arr1 = ["a1", "a2", "a3"],
arr2 = ["b1", "b2", "b3"],
arr3 = ["c1", "c2", "c3"];

我們將所有陣列添加到一個變數中

let allArr = [arr1, arr2, arr3];

我們制作一個陣列來提供所有新陣列

let resultArr = [];

我們使第一個回圈在每個陣列中回圈

for (let i = 0; i < allArr.length; i  ) {

我們創建一個名為 res 的陣列來創建新陣列

let res = [];

我們在allArr變數上創建另一個回圈，但是為了改變我們使用一個foreach回圈

  allArr.forEach((arr) => {
    res.push(arr[i]);
  });

然后我們將 res 添加到resultArrVairable 之后

resultArr.push(res);

我們關閉了回圈

}

這是你的代碼

let arr1 = ["a1", "a2", "a3"],
  arr2 = ["b1", "b2", "b3"],
  arr3 = ["c1", "c2", "c3"];

let allArr = [arr1, arr2, arr3];
let resultArr = [];
for (let i = 0; i < allArr.length; i  ) {
  let res = [];
  allArr.forEach((arr) => {
    res.push(arr[i]);
  });
  resultArr.push(res);
}

我添加此回圈以僅在控制臺中記錄陣列。現場觀看

resultArr.forEach((arr) => {
  console.log(arr);
});

let arr1 = ["a1", "a2", "a3"],
  arr2 = ["b1", "b2", "b3"],
  arr3 = ["c1", "c2", "c3"];

let allArr = [arr1, arr2, arr3];
let resultArr = [];
for (let i = 0; i < allArr.length; i  ) {
  let res = [];
  allArr.forEach((arr) => {
    res.push(arr[i]);
  });
  resultArr.push(res);
}
resultArr.forEach((arr) => {
  console.log(arr);
});

我希望我的解釋很好:)

uj5u.com熱心網友回復：

這可能是實作預期目標的一種可能解決方案。

代碼片段

// method to transpose the arrays
const transpose = arr => {
  // first create a placeholder "result" 2D array
  const result = [
    ...Array(Math.min(
      ...arr.map(a => a.length)
    ))
  ].map((_, i) => [
    ...Array(arr[i].length)
  ].map(x => ""));
  
  // now, traverse through input 2D array & 
  // populate "result" by transposing row & col
  arr.forEach((row, rIdx) => 
    row.forEach((elt, cIdx) => 
      result[cIdx][rIdx] = elt
    )
  )
  
  return result;
};

const arrayOfArrays = [
  ["a1", "a2", "a3"],
  ["b1", "b2", "b3"],
  ["c1", "c2", "c3"]
];

console.log(
  'test case 1: ',
  JSON.stringify(arrayOfArrays),
  '\nresult: ',
  JSON.stringify(transpose(arrayOfArrays))
);

// using with the context of the question

const arr1 = ["a1", "a2", "a3"];
const arr2 = ["b1", "b2", "b3"];
const arr3 = ["c1", "c2", "c3"];

console.log(
  'using arr1, 2, 3: \n',
  JSON.stringify({arr1, arr2, arr3}),
  '\nraw-result: ',
  JSON.stringify(transpose([arr1, arr2, arr3]))
);

// getting the result arrays separately
const [arr4, arr5, arr6] = transpose([arr1, arr2, arr3]);

console.log(
  'showing result arrays arr4, 5, 6: \n',
  JSON.stringify({arr4, arr5, arr6})
);

// Testing with "20" element arrays

const alph = "abcdefghijklmnopqrstuvwxyz".split('');
const num = 20;
const twentyArr = [...Array(num).keys()].map(k => [...Array(num).keys()].map((_, i) => `${alph[k]}${i 1}`));

console.log(
  'Testing for twenty elements array: \n',
  JSON.stringify(twentyArr),
  '\nresult:\n',
  JSON.stringify(transpose(twentyArr))
);

.as-console-wrapper { max-height: 100% !important; top: 0 }

解釋

上面代碼段中提供的行內注釋。

標籤：javascript 数组

上一篇：基于第一列對二維陣列進行排序，其中值為“版本點”字串JS

下一篇：TypeScript：如何替換字串中的特定數字（數值和非數值的組合），然后更新其值？