Scala ListBuffer (or equivalent) shuffle

Question

Is there a simple shuffle function for Scala lists?

If not, whats the simplest way to implement?

I have a lot of these things to do all over the code, so the simpler the call, the best it is

An example in Ruby

a = [ 1, 2, 3 ]           #=> [1, 2, 3]
a.shuffle                 #=> [2, 3, 1] returns new array shuffled

Thanks in advance :)

Have you looked at using [Collections.shuffle()][1] ? [1]: http://stackoverflow.com/questions/1259223/how-to-use-java-collections-shuffle-on-a-scala-array?rq=1 — Brian Agnew, Jun 14 '12 at 19:57

Tomasz Nurkiewicz · Accepted Answer · 2012-06-14T20:53:46.763

41

In Scala you can use scala.util.Random:

util.Random.shuffle((1 to 10).toSeq)
//Vector(9, 6, 8, 7, 10, 1, 2, 5, 3, 4)

util.Random.shuffle(List('A', 'B', 'C', 'D', 'E', 'F'))
//List(B, D, A, E, C, F)

Your results may vary...

edited Jun 14 '12 at 20:53

answered Jun 14 '12 at 20:03

Tomasz Nurkiewicz

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Very nice and clean, but for some reason it didn't worked with Array[Objects], only with Lists and ListBuffers (using 2.8) – rdlu Jun 14 '12 at 20:30
@rodrigo.dk The collection has to be something that implements the trait TraversableOnce. Try ArrayBuffer for example. – Brian Jun 14 '12 at 20:57
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@rodrigo.dk use java.util.Collections.shuffle for arrays – Luigi Plinge Jun 14 '12 at 23:24
@LuigiPlinge That's for for java arrays. – worldsayshi Nov 14 '13 at 21:49
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@worldsayshi java and Scala arrays are the same thing. – Luigi Plinge Nov 15 '13 at 03:05
Oh, I had the shallow impression that the collections implementations were disparate. – worldsayshi Nov 16 '13 at 21:52
@LuigiPlinge the signature of `java.util.Collections.shuffle` is `public static void shuffle(List> list)`, how can you shuffle an array with that? I suppose you meant `ArrayList`s? – Zoltán Dec 28 '14 at 14:19
@Zoltán good point. I don't know the solution off the top of my head; you might like to post a question if google doesn't turn up anything. – Luigi Plinge Dec 28 '14 at 15:48

Scala ListBuffer (or equivalent) shuffle

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