Ramda GroupBy - 如何按任何道具分组

Question

给定：

interface Dict {
  [key: string]: any
}

const data: Dict[] = [
  { id: 'a' },
  { id: 'b', b: 'something' },
  { id: 'c', b: 'else' },  
  { id: 'd', extra: 'hello world' },
  { id: 'e' },  
];

未指定这些 Dict 对象的键...

我怎样才能得到这个结果？

const result = {
  id: ['a', 'b', 'c', 'd', 'e'],
  b: ['something', 'else'],
  extra: ['hello world'],
  // ... and any other possible key
}

Answer 1

使用 R.reduce 和 R.mergeWith 并连接所有项目：

const { mergeWith, reduce } = R

const fn = reduce(mergeWith((a, b) => [].concat(a, b)), {})


const data = [
  { id: 'a' },
  { id: 'b', b: 'something' },
  { id: 'c', b: 'else' },  
  { id: 'd', extra: 'hello world' },
  { id: 'e' },  
];

const result = fn(data)

console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.js"></script>

如果您还需要数组中的单个值 (extra)，请映射项目，并用数组包装，只是已经不是数组的值：

const { pipe, mergeWith, reduce, map, unless, is, of } = R

const fn = pipe(
  reduce(mergeWith((a, b) => [].concat(a, b)), {}),
  map(unless(is(Array), of))
)


const data = [
  { id: 'a' },
  { id: 'b', b: 'something' },
  { id: 'c', b: 'else' },  
  { id: 'd', extra: 'hello world' },
  { id: 'e' },
];

const result = fn(data)

console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.js"></script>

Answer 2

您可以将对象展平成对列表，将其分组，然后将对转换回值：

const data = [
  { id: 'a' },
  { id: 'b', b: 'something' },
  { id: 'c', b: 'else' },  
  { id: 'd', extra: 'hello world' },
  { id: 'e' },  
];


let z = R.pipe(
  R.chain(R.toPairs),
  R.groupBy(R.head),
  R.map(R.map(R.last))
)

console.log(z(data))

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.js"></script>

Answer 3

与 Ori Drori 的回答略有不同： （假设您的对象中的任何属性都已包含在数组中）

const data = [
  { id: 'a' },
  { id: 'b', b: 'something' },
  { id: 'c', b: 'else' },  
  { id: 'd', extra: 'hello world' },
  { id: 'e' }
];

const run = reduce(useWith(mergeWith(concat), [identity, map(of)]), {});

console.log(
  run(data)
)

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.min.js"></script>
<script>const {reduce, useWith, mergeWith, concat, identity, map, of} = R;</script>

Ramda GroupBy - 如何按任何道具分组

Ramda GroupBy - How to group by any prop

javascript

functional-programming

ramda.js

我怎样才能得到这个结果？