Nodejs – 通过添加具有相同键的值来返回键值对的数组

我有以下的对象数组：

const list = [ {points: 3, name:'bob'}, {points: 1, name:'john'}, {points: 5, name:'john'}, {points: 2, name:'john'}, {points: 8, name:'john'}, {points: 0, name:'bob'}, {points: 2, name:'bob'}, {points: 1, name:'bob'}, ] 

我想结束，并返回一个包含每个名称点的总和的数据集列表，如：

 const list2 = [ {name: 'bob', points: 6}, // sum of all of bob's points {name: 'john', points: 16} ] 

我需要这个，所以我可以使用生成的数据集来生成折线图。

有没有办法做到这一点，最好使用ramda.js ？

Answer 1

你可以这样做：

 var combine = pipe( groupBy(prop('name')), //=> {bob: [bob_obj_1, bob_obj_2, ...], john: [ ... ]} map(pluck('points')), //=> {bob: [3, 0, 2, 1], john: [1, 5, 2, 8]} map(sum) //=> {bob: 6, john: 16} ) 

或者你可以使用reduce ，但我认为这是更简单。

更新 ：我误读了输出格式。 这解决了它：

 var combine = pipe( groupBy(prop('name')), //=> {bob: [bob_obj_1, bob_obj_2, ...], john: [ ... ]} map(pluck('points')), //=> {bob: [3, 0, 2, 1], john: [1, 5, 2, 8]} map(sum), //=> {bob: 6, john: 16} toPairs, //=> [["bob", 6], ["john", 16]] map(zipObj(['name', 'points'])) //=> [{name: "bob", points: 6}, // {name: "john", points: 16}] ) 

Answer 2

这是一个相当简单的使用Array.prototype.reduce（）和Object.keys（） ：

 const list = [ {points: 3, name:'bob'}, {points: 1, name:'john'}, {points: 5, name:'john'}, {points: 2, name:'john'}, {points: 8, name:'john'}, {points: 0, name:'bob'}, {points: 2, name:'bob'}, {points: 1, name:'bob'}, ] const map = list.reduce((prev, next) => { // if the name has not already been observed, create a new entry with 0 points if (prev[next.name] == null) { prev[next.name] = 0; } // add the new points prev[next.name] += next.points; return prev; }, {}); // map is now an object containing { [name]: [points] } // convert this back into an array of entries const list2 = Object.keys(map) .map(name => ({ name, points: map[name] })); console.log(list2) // [ { name: 'bob', points: 6 }, { name: 'john', points: 16 } ]