How to sort a list on another list in lodash

Question

Gived a list

[
{id:'i1',value:'v1'},
{id:'i3',value:'v3'},
{id:'i4',value:'v4'},
{id:'i2',value:'v2'},
{id:'i5',value:'v5'},
]

and another ordered id list

['i1','i2','i3','i4','i5']

get

[
{id:'i1',value:'v1'},
{id:'i2',value:'v2'},
{id:'i3',value:'v3'},
{id:'i4',value:'v4'},
{id:'i5',value:'v5'},
]

How to do this in lodash?

will these lists have always the same elements or could it be that they are 'off' on certain elements? — Falk
– Falk, Commented Sep 17, 2018 at 7:04
@Falk The lists may have any elements with a random id. Actually the data list is queried by id list from server. But the server can't promise the order of data will not be changed so I need to sort the data manually. — lei li
– lei li, Commented Sep 17, 2018 at 7:15

suDocker · Accepted Answer · 2018-09-17 07:21:23Z

2

Use sortBy method and return the id's index position from the iteratee function

let sortedArray = _.sortBy(input, (v) => order.indexOf(v.id))

where

input = [
  {id:'i1',value:'v1'},
  {id:'i3',value:'v3'},
  {id:'i4',value:'v4'},
  {id:'i2',value:'v2'},
  {id:'i5',value:'v5'},
]
order = ['i1','i2','i3','i4','i5']

answered Sep 17, 2018 at 7:21

suDocker

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2 Comments

lei li Over a year ago

I think this is a better answer. Thank everyone.

Buggy Over a year ago

It is worth mentioning that (v) => order.indexOf (v.id) is called N times, and order.indexOf has complexity O(N).

Buggy · Accepted Answer · 2018-09-17 07:11:08Z

0

Convert Array to Object where key is id for better lookup. Replace each element in ordered list with actual value.

Edge case: the two array has the same elements

const foo = [
  {id:'i1',value:'v1'},
  {id:'i3',value:'v3'},
  {id:'i4',value:'v4'},
  {id:'i2',value:'v2'},
  {id:'i5',value:'v5'},
];

const ordered = ['i1','i2','i3','i4','i5'];

const fooMap = _.keyBy(f, 'id');

const orderedFoo = ordered.map(id => fooMap[id])

answered Sep 17, 2018 at 7:11

Buggy

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Comments

Lazar Nikolic · Accepted Answer · 2018-09-17 07:15:34Z

0

const arr = ['i1','i2','i3','i4','i5'];
const arrObj = [
{id:'i1',value:'v1'},
{id:'i3',value:'v3'},
{id:'i4',value:'v4'},
{id:'i2',value:'v2'},
{id:'i5',value:'v5'}
]
const sortedArr = [];

_.map(arr, a => sortedArr.push(_.find(arrObj, ['id', a])));
console.log(sortedArr)

answered Sep 17, 2018 at 7:15

Lazar Nikolic

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Comments

alalalala · Accepted Answer · 2018-09-17 07:26:59Z

0

let arr = ['i1','i2','i3','i4','i5'];
let arrObj = [
    {id:'i1',value:'v1'},   
    {id:'i3',value:'v3'},
    {id:'i4',value:'v4'},
    {id:'i2',value:'v2'},
    {id:'i5',value:'v5'}
]

console.table(arrObj);

arr.map(v => {
    arrObj.sort( v1 => { return v1.id == v ? true : false} )
})

console.table(arrObj);

answered Sep 17, 2018 at 7:26

alalalala

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