Make nulls always last when sorting

Question

I am using underscore to sort an array. Is there a way to make nulls always last whether ascending or descending? For example:

[
    { name: 'a', age: 1 }, 
    { name: 'z', age: 5 }, 
    { name: '', age: 1 }, 
    { name: 'v', age: 7 }
]

Will produce

[
    { name: 'a', age: 1 }, 
    { name: 'v', age: 7 }, 
    { name: 'z', age: 5 }, 
    { name: '', age: 1 }
]

and descending will produce:

[
    { name: 'z', age: 5 }, 
    { name: 'v', age: 7 }, 
    { name: 'a', age: 1 }, 
    { name: '', age: 1 }
]

My real array is an array of objects so i have to pluck values out.

You can remove all the null values, why put them on the end? — Bazinga, Nov 23 '14 at 20:18
I am trying to sort a property on an object. So even if a property is null the other properties are useful. — Luke101, Nov 23 '14 at 20:22
@anguLaravel I have edited the question to make it simpler and clearer. — Luke101, Nov 23 '14 at 20:32
@Luke101 You edited your question but based on the old question I've added an example for you. — istos, Nov 23 '14 at 20:38
https://stackoverflow.com/questions/29829205/sort-an-array-so-that-null-values-always-come-last/29829370#29829370 — Amir Ali, Apr 14 '20 at 20:58

istos · Accepted Answer · 2014-11-24T00:16:01.810

6

There are many ways to go about it but you could try something like this:

var arr = [{name: 'a', age: 1}, {name: 'z', age: 5}, {name: '', age: 1}, {name: 'v', age: 7 }];

_.chain(arr)
 .sortBy('name')
 //.reverse() // to sort descending
 .partition('name')
 .flatten()
 .value();

Result:

[ { name: 'a', age: 1 },
  { name: 'v', age: 7 },
  { name: 'z', age: 5 },
  { name: '', age: 1 } ]

edited Nov 24 '14 at 00:16

answered Nov 23 '14 at 20:35

istos

2,654
1
17
19

This doesn't sort. -1 – Scimonster Nov 23 '14 at 20:39
He didn't ask to sort. – istos Nov 23 '14 at 20:40
Maybe he doesn't come out and say "SORT THIS", but that's the way i understand the question. (Also there's a comment to that effect.) – Scimonster Nov 23 '14 at 20:40
I've edited your code to match the OP's update. Hope you don't mind. – georg Nov 23 '14 at 21:03
@georg yeah that's fine. – istos Nov 23 '14 at 21:28

score 1 · Answer 2 · answered Nov 23 '14 at 20:57

You can do this with lodash, and im think underscore as this function too.

var users =[{name: 'a', age: 1}, {name: '', age: 4}, {name: 'z', age: 5}, {name: '', age: 1}, {name: 'v', age: 7 }];

_.sortBy(users, 'name');

The results will give you the null names in the beginning:

[{name: '', age: 1}, {name: '', age: 4}, {name: 'a', age: 1}, {name: 'z', age: 5}, {name: 'v', age: 7 }];

score 0 · Answer 3 · answered Nov 23 '14 at 20:36

0

You could simply find them after sorting and put them in the back manually. Maybe by splitting the different values in 2 arrays and then concatenating them. One of the arrays contains non null values and the other the null values

answered Nov 23 '14 at 20:36

Kokozaurus

639
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22

Make nulls always last when sorting

3 Answers3