转换对象数组 post 将它们分成两半：Javascript

Question

我有一个类似于这样的对象数组：

arr = [{ val: 1, ts : 123},{val: 2, ts : 125},{val: 3,ts : 120}, {val: 4, ts : 113} , {val:5, ts : 117},{ val: 6, ts : 143},{val: 7, ts : 193},{val: 8, ts : 187}, {val: 9, ts : 115} , {val:10,ts : 116}]

数组的长度总是偶数。现在基本上我想把它们分成两半。

split1 = [{ val: 1, ts : 123},{val: 2, ts : 125},........,{val:5, ts : 117}]
split2 = [{ val: 6, ts : 143},{val: 7, ts : 193},........,{val:10,ts : 116}]

我必须映射这些数组并转换它们的字段（array1 的第一项与 array2 的第一项等等）。假设第一个数组称为 "old" array with objects having(keys val and ts) 第二个数组称为 "new" array with objects having(keys val and ts) 。所以我已经映射了它们，最终应该是这样的

final = [
          { oldVal:1, oldts: 123 , newVal:6, newts: 143},
          { oldVal:2, oldts: 125 , newVal:7, newts: 193},
          { oldVal:3, oldts: 120 , newVal:8, newts: 187},
          { oldVal:4, oldts: 113 , newVal:9, newts: 115},
          { oldVal:5, oldts: 117 , newVal:10, newts: 116},
        ]

我试过的是：

var res= a.splice(0, arr.length/2);
var c = a.map((val, ind) => { {val, res[ind]} })

有人可以指导吗？

Answer 1

您可以简单地遍历数组的一半，并将第 i 个元素和第 i + half 个作为其对：

const arr = [{ val: 1, ts : 123},{val: 2, ts : 125},{val: 3,ts : 120}, {val: 4, ts : 113} , {val:5, ts : 117},{ val: 6, ts : 143},{val: 7, ts : 193},{val: 8, ts : 187}, {val: 9, ts : 115} , {val:10,ts : 116}];

const final = [];
const half = arr.length / 2;
for (let i = 0; i < half; i++) {

  final.push({
    oldVal: arr[i].val,
    oldTs: arr[i].ts,
    newVal: arr[i + half].val,
    newTs: arr[i + half].ts,
  });
}

console.log(final);

Answer 2

我不确定你是否必须对数组进行切片，但这是我的方法:

arr = [{ val: 1, ts : 123},{val: 2, ts : 125},{val: 3,ts : 120}, {val: 4, ts : 113} , {val:5, ts : 117},{ val1: 6, ts : 143},{val1: 7, ts : 193},{val1: 8, ts : 187}, {val1: 9, ts : 115} , {val1:10,ts : 116}];
let final = [];
arr.forEach(function(v, i) {
    if (i >= arr.length / 2) return false;
    final[i] = {oldVal: v.val, oldTs: v.ts, newVal: arr[i + arr.length / 2].val, newTs: arr[i + arr.length / 2].ts}
});
console.log(final)

Answer 3

您可以采用单循环方法并在数组循环时更改值。

var data = [{ val: 1, ts: 123 }, { val: 2, ts: 125 }, { val: 3, ts: 120 }, { val: 4, ts: 113 }, { val: 5, ts: 117 }, { val: 6, ts: 143 }, { val: 7, ts: 193 }, { val: 8, ts: 187 }, { val: 9, ts: 115 }, { val: 10, ts: 116 }],
    result = data.reduce((r, { val, ts }, i, { length }) => {
        const index = i % (length >> 1);
        if (r[index]) {
            r[index].newVal = val;
            r[index].newts = ts;
        } else {
            r[index] = { oldVal: val, oldts: ts };
        }
        return r;
    }, []);

console.log(result);

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

Answer 4

var newArr = [];
var half = Math.floor(arr.length / 2);

for (var i = 0; i < half; i++){
    newArr.push({oldVal: arr[i].val, oldTs: arr[i].ts, newVal: arr[i + half].val, newTs: arr[i + half].ts}) 
}

**P.S 如果您的原始数组长度为偶数，您将有剩余项

转换对象数组 post 将它们分成两半：Javascript

Convert array of objects post splitting them in half: Javascript

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arrays

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