通过重复键合并数组的值 [英] Merge values of array by duplicate keys

问题描述

尝试合并json数组的重复键并以csv格式构建各自的值.

Trying to merge duplicate keys of json array and build respective values in csv format.

A=[{a:1,b:2},{a:1,b:1},{a:1,b:6},{a:2,b:5},{a:2,b:3}]

尝试进行转换

A=[{a:'1',b:'2,1,6'},{a:2,b:'5,3'}]

我尝试过的代码

var existingIDs = [];
        A= $.grep(A, function (v) {
            if ($.inArray(v.a, existingIDs) !== -1) {
                return v.b+= ',';
            }
            else {
                existingIDs.push(v.a);
                return true;
            }
        });

输出类似于

A=[{a:1,b:2},{a:1,b:'1,'},{a:1,b:'6,'},{a:2,b:5},{a:2,b:'3,'}]

推荐答案

使用a中的1，2等作为键创建一个临时对象，并继续添加b值，然后对其进行迭代创建新数组的对象:

Create a temporary object with 1, 2 etc from a as keys and keep adding on the b values, then iterate over that object creating the new array :

var A = [{a:1,b:2},{a:1,b:1},{a:1,b:6},{a:2,b:5},{a:2,b:3}];
var temp = {};

for (var i=0; i<A.length; i++) {
    temp[A[i].a] =
        temp[A[i].a] === undefined ?
            A[i].b :
            temp[A[i].a] + ',' + A[i].b;
}

A = [];

for (var key in temp) {
    A.push({a: key, b:temp[key]})
}

FIDDLE

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