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Please add some code with Mutidimensional arrays

2 replies on 1 page. Most recent reply: Jan 29, 2008 10:04 PM by Eric Willigers

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Javier Diaz Soto

Posts: 29
Nickname: javierbds
Registered: Sep, 2005

Please add some code with Mutidimensional arrays

Posted: Jan 22, 2008 5:58 AM

I found no mention if them and, as they are so different from C-like (and as all functional languages try to force you to use inmutable lists ...)
It makes it difficult, at first, to try things:

var a = new Array[Array[Int]](2,3)
a(0)(1)=4

Is there some sugar for specifying the type?
Is there a simpler syntax?

Javier Diaz Soto

Posts: 29
Nickname: javierbds
Registered: Sep, 2005

Re: Please add some code with Mutidimensional arrays

Posted: Jan 22, 2008 6:05 AM

On the other hand, these are not really multidimensional arrays (I think). Memory seems not to be contiguous and offset calculations cannot be used to position yourself (you seem to need indirection, 1 jump per additional dimension) ... Maybe it is optimized under the hood? If this is not so, how could we use Java multidim arrays in Scala source code?

Eric Willigers

Posts: 8
Nickname: ewilligers
Registered: Dec, 2007

Re: Please add some code with Mutidimensional arrays

Posted: Jan 29, 2008 10:04 PM

Scala doesn't have multidimensional arrays. Instead it has arrays of any element type, so you can create arrays of arrays. There are a couple of old examples in the language spec (search for "matrix"); here's some corrected code for those examples:
https://lampsvn.epfl.ch/trac/scala/attachment/ticket/421/MatrixExamples.scala

There are methods for constructing arrays of arrays of arrays of ...:-
val x = new Array[Array[Array[Int]]](2, 3, 4)
x(0) = new Array[Array[Int]](1, 1)
println( x.map(y => y.map(_.toList)).map(_.toList).toList )

List(List(List(0)), List(List(0, 0, 0, 0), List(0, 0, 0, 0), List(0, 0, 0, 0)))

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