通过“组"对二维数组求和 [英] Summing a 2D array by "group"

问题描述

我在表单中有一个数组

[
['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缩减为唯一的左侧条目.这是我想减少到的一个例子

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人为的例子.我查看了 javascript 的数组 reduce，但我不确定如何使用它来实现此效果

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，map()改成你想要的格式.

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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