GROUP BY和点心使用下划线/ Lodash [英] Group By and Sum using Underscore/Lodash

问题描述

我有JSON是这样的：

I have JSON like this:

[
  {
     platformId: 1,
     payout: 15,
     numOfPeople: 4
  },
  {
     platformId: 1,
     payout: 12,
     numOfPeople: 3

  },
  {
     platformId: 2,
     payout: 6,
     numOfPeople: 5

  },
  {
     platformId: 2,
     payout: 10,
     numOfPeople: 1
  },

]

和我想集团是由<$​​ C $ C> platformId 与派息和 numOfPeople <总和/ code>。

And I want to Group it by platformId with sum of payout and numOfPeople.

即。在结果我想JSON是这样的：

I.e. in result I want JSON like this:

[
  "1": {
     payout: 27,
     numOfPeople: 7
   },

  "2": {
     payout: 16,
     numOfPeople: 6
  }
] 

我试图用 underscore.js 的 _。GROUPBY 方法，并且它团体罚款，但如何我可以得到对象的属性值的总和就像我上面证明？

I tried to use underscore.js's _.groupBy method, and it groups fine, but how I can get the SUM of objects properties values like I demonstrated above?

推荐答案

可以做到这一点，没有下划线：

You can do this without Underscore:

var result = data.reduce(function(acc, x) {
  var id = acc[x.platformId]
  if (id) {
    id.payout += x.payout
    id.numOfPeople += x.numOfPeople
  } else {
    acc[x.platformId] = x
    delete x.platformId
  }
  return acc
},{})

但是，为什么你想用数字键的对象？你可以将其转换回一个集合：

But why would you want an object with numeric keys? You could convert it back to a collection:

var toCollection = function(obj) {
  return Object.keys(obj)
    .sort(function(x, y){return +x - +y})
    .map(function(k){return obj[k]})
}

toCollection(result)

注意，对象都发生突变，所以你可能他们先克隆，如果你想保持原来的数据。

Note that objects are mutated, so you may to clone them first if you want to maintain the original data.

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