Select an array from an array in perl

Question

I'd like to do the following in Perl:

my @triples=([3,4,5],[5,12,13],[8,5,17],[7,24,25]};

Then I want to select one of the four triples at random, then assign the elements of the selection to the variables x, y, and r.

For example, if [3,4,5] is selected at random, assign x= 3, y = 4, r =5.

Any suggestions?

Perfect answer! It works just as a needed it to work. Thanks. — David
– David, Commented Dec 17, 2014 at 2:55

Patrick J. S. · Accepted Answer · 2014-12-17 14:27:54Z

4

An integer between 0 and 4 (4 exclusive):

int(rand 4).

Use this as the array index:

$triplets[int(rand 4)]

now dereference and assign to your variables:

my ($x, $y, $r) = @{$triplets[int(rand 4)]}

as @Jim Davids has pointed out, you can drop the int and to get a more general approach, you can use @triplets in scalar context to get the length of the array.

my ($x, $y, $r) =  @{$triplets[rand @triplets]}

edited Dec 17, 2014 at 14:27

answered Dec 17, 2014 at 4:16

Patrick J. S.

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3 Comments

Jim Davis Over a year ago

Since perl will truncate a float when specified as an array index, you don't need int. And since @arr in scalar context returns the size of the array, you could drop the hard-wired 4 and do ...= @{$triplets[rand @$triplets]}

Patrick J. S. Over a year ago

@Jim Davids: Thanks I edited that in, but @$triplets is an array dereference of $triplets, so I replaced it with @triplets since rand enforces scalar context

Jim Davis Over a year ago

Oh, right, sorry. Thought I was working with an array reference of array references for a minute there.

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