Sorting object by value

Question

I can imagine this has been asked a few times but I literally cannot find an example of a solution to the specific problem I'm trying to figure out.

So I have an object, like so:

var collection = [{ id: 0 }, { id: 1 }, { id: 2 }];

I then have an array, which is the 'order', like so:

var order = [2, 0, 1];

I want to use the 'order' array to reorder the collection in that specific order. I've been trying quite a few solutions with the .sort function, but I can't find one that fits. Can anyone enlighten me? Probably simple, I'm hoping.

Not sure what your needs are but in such a simple case you could order by index. — elclanrs
– elclanrs, Commented Feb 10, 2013 at 23:42
Be wary of solutions that use multiple, uncached calls to indexOf, since they will involve sweeping through order many, many times. — Dancrumb
– Dancrumb, Commented Feb 10, 2013 at 23:46

ozk · Accepted Answer · 2013-02-10 23:40:57Z

You can use the sort() method to accomplish this using indexOf:

collection.sort(function(a, b){ return order.indexOf(a.id) > order.indexOf(b.id); });

Styxxy · Accepted Answer · 2013-02-10 23:43:52Z

2

You can use indexOf function on the order array in the custom sort function, like this:

collection.sort(function(x, y) { return order.indexOf(x.id) > order.indexOf(y.id); });

answered Feb 10, 2013 at 23:43

Styxxy

7,5473 gold badges43 silver badges48 bronze badges

2 Comments

Styxxy Over a year ago

Seems like I need to type faster, @ozk is faster than me :(.

ozk Over a year ago

StackOverflow is all about typing agility :)

pwolaq · Accepted Answer · 2013-02-10 23:37:59Z

1

seems to be as easy as that:

var collection = [{ id: 0 }, { id: 1 }, { id: 2 }]; var order = [2, 0, 1]; var sorted = []; for(var i=0,c=order.length;i<c;i++){ sorted.push(collection[order[i]]); }

answered Feb 10, 2013 at 23:37

pwolaq

6,41221 silver badges45 bronze badges

1 Comment

Dancrumb Over a year ago

I don't think that does what the OP is asking for. That takes collection and uses order to say "list the third, then the first, then the second from collection". I think that OP wants "list id:2, then id:0, then id:1"

mika · Accepted Answer · 2013-02-10 23:40:07Z

Try that:

var collection = [{ id: 0 }, { id: 1 }, { id: 2 }]; var order = [2, 0, 1]; var sortedCollection = []; for ( var i = 0; i < order.length; i++ ) sortedCollection.push(collection[order[i]]); console.log(sortedCollection);

Dancrumb · Accepted Answer · 2013-02-10 23:45:05Z

The thing you want to avoid here is scanning through either of these arrays more than you have to.

Here's one solution that avoids this:

/* * Map the indexes of the objects in collection to their final location */ var sortIndex = {}; order.forEach(function(value, index) { sortIndex[value] = index; }); /* * Put the objects in collection into their new, sorted collection */ var sortedCollection = []; collection.forEach(function(value) { var sortedLocation = sortIndex[value.id]; sortedCollection[sortedLocation] = value; });

Thus, we have a single scan through each of the arrays, keeping the work down to a minimum.

I've used forEach here as a convenience; you could use a library like Lodash or Underscore, or rewrite this to use explicit iteration over the arrays.

Collectives™ on Stack Overflow

Sorting object by value

5 Answers 5

Comments

2 Comments

1 Comment

Comments

Comments

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

2 Comments

1 Comment

Comments

Comments

Related