How to sort different arrays of objects inside an array

Question

How to sort separately 2 arrays of objects inside an array ? A solution with Lodash needed. Thank you.

Example of Array to sort by year:

var objects = [[{
      year: 2010,
      name: "john",
      value: 30
    },
    {
      year: 2009,
      name: "john",
      value: 40
    }
  ],
  [{
      year: 2018,
      name: "bob",
      value: 40
    },
    {
      year: 2015,
      name: "bob",
      value: 30
    }]]

Desired output after sorting by year:

[[{
      year: 2009,
      name: "john",
      value: 40
    },
    {
      year: 2010,
      name: "john",
      value: 30
    }
  ],
  [{
      year: 2015,
      name: "bob",
      value: 30
    },
    {
      year: 2018,
      name: "bob",
      value: 40
    }]]

Possible duplicate of Sort array of objects by string property value — Webber
– Webber, Commented May 12, 2019 at 10:11

Krzysztof Krzeszewski · Accepted Answer · 2019-05-12 10:13:27Z

2

orderBy on every sub collection should suffice

var objects = [
[{
year: 2010,
name: "john", 
value: 30
},
{
year: 2009,
name: "john",
value: 40
}],
[{
year: 2018,
name: "bob", 
value: 40
},
{
year: 2015,
name: "bob",
value: 30
}]
]

console.log(objects.map(subObject => _.orderBy(subObject, "year")));

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>

answered May 12, 2019 at 10:13

Krzysztof Krzeszewski

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Comments

Maheer Ali · Accepted Answer · 2019-05-12 10:22:10Z

1

You can use map() on array of arrays and return the sorted array in map function.

var arr = [[{year:2010,name:"john",value:30},{year:2009,name:"john",value:40}],[{year:2018,name:"bob",value:40},{year:2015,name:"bob",value:30}]];


const res = arr.map(x => x.slice().sort((a,b) => a.year - b.year));
console.log(res)

edited May 12, 2019 at 10:22

answered May 12, 2019 at 10:12

Maheer Ali

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5 Comments

Amit Baranes Over a year ago

why did you use slice ?

Maheer Ali Over a year ago

@AmitBaranes sort() modifies the original array. If i wouldn't have used slice() the origianal array whould have changed. Its just to make a copy of array.

Amit Baranes Over a year ago

Nice, didn't know that :)

Isaac Over a year ago

@MaheerAli: I don't get it actually, coz when I do console.log(arr), it appears to me that arr remained the same while res is sorted. May I know how to prove what you're saying

Maheer Ali Over a year ago

@Isaac I am saying that if you don't use slice() then the original array i.e arr will be changed. In my code I am using slice() so arr remains same. Remove slice() you will see array is modified and becomes sorted.

Amit Baranes · Accepted Answer · 2019-05-12 10:12:55Z

0

You need to map the array and than sort it :

const objects = [
[{
year: 2010,
name: "john", 
value: 30
},
{
year: 2009,
name: "john",
value: 40
}],
[{
year: 2018,
name: "bob", 
value: 40
},
{
year: 2015,
name: "bob",
value: 30
}]
] 

const sorted = objects.map(r=>r.sort((a,b)=>a.year - b.year));

console.log(sorted)

answered May 12, 2019 at 10:12

Amit Baranes

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Comments

Ori Drori · Accepted Answer · 2019-05-12 10:35:44Z

You can generate a function with _.partialRight() and _.map() to _.sortBy() the sub arrays:

const { partialRight: pr, map, sortBy } = _;

const sortSubArrays = pr(map, arr => sortBy(arr, 'year'));

const objects = [[{year:2010,name:"john",value:30},{year:2009,name:"john",value:40}],[{year:2018,name:"bob",value:40},{year:2015,name:"bob",value:30}]];

const output = sortSubArrays(objects);

console.log(output);

.as-console-wrapper { max-height: 100% !important; top: auto; }

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"></script>

Or use lodash/fp and drop the partialRight:

const { map, sortBy } = _;

const sortSubArrays = map(sortBy('year'));

const objects = [[{year:2010,name:"john",value:30},{year:2009,name:"john",value:40}],[{year:2018,name:"bob",value:40},{year:2015,name:"bob",value:30}]];

const output = sortSubArrays(objects);

console.log(output);

.as-console-wrapper { max-height: 100% !important; top: auto; }

<script src='https://cdn.jsdelivr.net/g/lodash@4(lodash.min.js+lodash.fp.min.js)'></script>

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