通过“分组"对2D阵列求和. [英] Summing a 2D array by "group"

问题描述

我有一个数组，形式为

[
['16-24', 192081],
['16-24', 94452],
['16-24', 1055],
['25-34', 192081],
['25-34', 94452],
['25-34', 1055],
...
]

我想将数组中的许多项目简化为唯一的左侧条目.这是我想简化为

I have many items in the array that I'd like to reduce down to the unique left-hand entries. This is an example of what I'd like to reduce down to

[
['16-24', 287588],
['25-34', 287588],
...
]

显然，这里的数字是一个虚构的示例.我已经研究了javascript的array reduce，但是不确定如何使用它来实现这种效果.

Obviously the numbers here are a contrived example. I've looked into javascript's array reduce but I'm unsure how to use it to achieve this effect

推荐答案

使用 reduce()求和，并 map()将其更改为所需的格式.

Use reduce() to sum and map() to change it to the format you want.

var vals = [
['16-24', 192081],
['16-24', 94452],
['16-24', 1055],
['25-34', 192081],
['25-34', 94452],
['25-34', 1055]
];

var temp = vals.reduce(function (obj, cur) {
    var total = obj[cur[0]] || 0;
    obj[cur[0]] = total + cur[1];
    return obj;
}, {} );

var result = Object.keys(temp).map( function (key) { return [key, temp[key]]; });
console.log(result);                                                             

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