Comments on: AS3: Removing duplicates from an array

By: Ash

Ash — Fri, 22 May 2009 13:44:00 +0000

Thanks for your findings Aurelain. I originally posted this as an interesting snippet and made no claims for performance. In a real world application, I would definitely recommend using something a little more readable/sensible.

By: Aurelain

Aurelain — Fri, 22 May 2009 10:15:22 +0000

A note about performance:
saulo's code is about 2% faster then Razorberry's.

Also, if saulo would add variable types, the code would get a 10% performance boost. Like this:

arr.filter(function(e:*, i:int, a:Array):Boolean {return a.indexOf(e) == i;});

By: Aurelain

Aurelain — Fri, 22 May 2009 10:08:29 +0000

Razorberry's code:
- Adds the first element into the new array
- Any subsequent element gets tested whether it already exists or not. If not, pushes the element into the new array.

On the other hand, saulo's code is much more elegant:
- Each element's index is compared to the index of its first occurrence. If they're different, it means the element is not the first, thus a duplicate.

By: marije

marije — Thu, 16 Apr 2009 11:18:35 +0000

It works perfectly! Wish I could understand how it works.

By: laku matu

laku matu — Tue, 10 Mar 2009 20:45:24 +0000

yeah, please
i only half understand it

By: saicolo

saicolo — Thu, 26 Feb 2009 20:14:00 +0000

Can you explain how it works so us lames can understand whats going on? Thanks =)

By: chet

chet — Sat, 20 Dec 2008 04:30:12 +0000

Wow, that is inline to the extreme. Nice work but it doesn't always have to be on one line (thanks for the function)

By: saulo

saulo — Mon, 15 Dec 2008 19:56:12 +0000

what about
var a:Array = ["1", "1", "3", "3"];
trace(a.filter(function(e, i, a) {
return a.indexOf(e) == i;
}, this));
?

By: vitaLee

vitaLee — Thu, 04 Dec 2008 09:06:37 +0000

well, it's hell of a long line of code.

By: Simon B

Simon B — Thu, 23 Oct 2008 03:33:02 +0000

Thanks for the script!

I've been trying all sorts of things to cut out duplicates, but I'm not a programmer so it's been taking me forever!

Simon.