Question

我有以下数组，包括name，age和department

[[ "Kevin", 22,"Psychology" ],
[ "Cathy", 26, "Psychology" ],
[ "David", 31, "Engineering" ],
[ "Christine", 23, "Engineering" ]]

我想基于独特的departments创建一个如下所示的地图：

{ Psychology: [ 
  { name: "Cathy", age: 26 }, 
  { name: "Kevin", age: 22 } ] 
},
{ Engineering: [ 
  { name: "Christine", age: 23 }, 
  { name: "David", age: 31 } ] 
}

数组中department的索引始终相同。如何利用lodash？

完成此操作

Answer 1

不使用外部库，使用新的ESNext这样的东西非常简单。

const data = [
[ "Kevin", 22,"Psychology" ],
[ "Cathy", 26, "Psychology" ],
[ "David", 31, "Engineering" ],
[ "Christine", 23, "Engineering" ]];

const result = data.reduce((a, v) => {
  const [name,age,dept] = v; 
  (a[dept] = a[dept] || []).push({name,age});
  return a;
}, {});

console.log(result);

Answer 2

这是一个lodash解决方案：

const {flow, groupBy, nth, mapValues, map, zipObject} = _

const transform = flow(
  people => groupBy(people, p => nth(p, 2)),
  grouped => mapValues(grouped, dept => map(
    dept, 
    person => zipObject(['name', 'age'], person)
  ))
)

const people = [["Kevin", 22, "Psychology"], ["Cathy", 26, "Psychology"], ["David", 31, "Engineering"], ["Christine", 23, "Engineering"]]

console.log(transform(people))

<script src="//cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js"></script>

使用lodash / fp可能会更简单，但我从来没有让它正常工作。我可能没有花太多时间在上面，因为我是JS的另一个FP库Ramda的作者之一。上面的解决方案是通过翻译我的第一个代码创建的，用Ramda编写：

const {pipe, groupBy, nth, map, zipObj} = R;

const transform = pipe(
  groupBy(nth(2)),
  map(map(zipObj(['name', 'age'])))
)

const people = [["Kevin", 22, "Psychology"], ["Cathy", 26, "Psychology"], ["David", 31, "Engineering"], ["Christine", 23, "Engineering"]]

console.log(transform(people))

<script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.js"></script>

我猜Lodash / fp代码可能看起来很相似，只是你必须用map替换第一个mapValues。

通过Lodash从数组创建对象的映射

2 个答案: