[英]Create array of objects using arrays of values
I have fairly lot of data in this form 我在这种形式中有相当多的数据
A B C D
-------
1 2 3 4
5 6 7 8
9 1 2 3
represented using javascript types as : 使用javascript类型表示为:
df = {A: [1,5,9], B: [2,6,1], C: [3,7,2], D:[4,8,3]}
I want to convert this into this form: 我想将其转换为这种形式:
[{A:1, B:2, C:3, D:4}, {A:5, B:6, C:7, D:8}, {A:9, B:1, C:2, D:3}]
I tried implementing it as: 我尝试将其实现为:
keyes = ["A", "B", "C", "D"]
getrow = (i) => Object.assign( ...keyes.map((k) => ({[k]: df[k][i]})))
df.A.map( (x,j) => getrow(j))
But this is slow for the size of the table I have. 但这对我所拥有的桌子的大小来说很慢。 Is there any faster way to do this?
有没有更快的方法来做到这一点?
You could use reduce
and forEach
loops to create array of objects. 您可以使用
reduce
和forEach
循环来创建对象数组。
const df = { A: [1, 5, 9], B: [2, 6, 1], C: [3, 7, 2], D: [4, 8, 3] } const result = Object.keys(df).reduce((r, k) => { df[k].forEach((e, i) => { if (!r[i]) r[i] = {} r[i][k] = e; }) return r; }, []) console.log(result)
Or maybe for better performance you can go with the for
loops. 或者为了获得更好的性能,您可以使用
for
循环。
const df = { A: [1, 5, 9], B: [2, 6, 1], C: [3, 7, 2], D: [4, 8, 3] } const result = []; for (let key in df) { for (let i = 0; i < df[key].length; i++) { if (!result[i]) result[i] = {} result[i][key] = df[key][i] } } console.log(result)
You could take two for loops, and check the existence of the object at a certain index. 您可以使用两个for循环,并检查某个索引处是否存在该对象。 Then assign the value to the property.
然后将值分配给属性。
This version is faster than the use of array methods. 这个版本比使用数组方法更快。
var data = { A: [1, 5, 9], B: [2, 6, 1], C: [3, 7, 2], D: [4, 8, 3] }, result = [], key, values, i; for ([key, values] of Object.entries(data)) { for (i = 0; i < values.length; i++) { if (!result[i]) result[i] = {}; result[i][key] = values[i]; } } console.log(result);
.as-console-wrapper { max-height: 100% !important; top: 0; }
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