Perl: How to access a hash with array values in a loop?

Question

I've defined a hash with arrays as values:

%myhash = ( 'key1' => [ 'key1value1', 'key1value2' ],
            'key2' => [ 'key2value1', 'key2value2' ],
            .......
            'key100' => [ 'key100value1', 'key100value2' ] );

How can we access the values of each key using a loop?

Basically, I want to do something like:

print "$myhash{'key1'}->[0]   and  $myhash{'key1'}->[1]\n";
print "$myhash{'key2'}->[0]   and  $myhash{'key2'}->[1]\n";
.......
print "$myhash{'key100'}->[0]   and  $myhash{'key100'}->[1]\n";

to print those two array values of each key in separate lines.

I've tried using an index in for/while loops with no success.

Thanks for any suggestions in advance!

reflective_mind · Accepted Answer · 2016-10-07 22:58:29Z

2

Here my solution...just for fun and maybe even more concise. Not sure if you can compress this even further:

print join ' ', @$_, "\n" for @myhash{sort keys %myhash};

Works for arbitrary long value arrays in %myhash.

EDIT:

As simbabque pointed out in the comments, it can indeed be further compressed. Thanks for the hint!

say join ' ', @$_ for @myhash{sort keys %myhash}; # requires: use feature 'say';

edited Oct 7, 2016 at 22:58

answered Oct 7, 2016 at 21:07

reflective_mind

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2 Comments

simbabque Over a year ago

Use say to make it shorter. But we are not on code golf. Short is not necessarily more concise. Sometimes it's just harder to read. ;-)

reflective_mind Over a year ago

Very nice thanks! No code golf, just a little bit of perl spirit ;)

Jim Garrison · Accepted Answer · 2016-10-07 16:00:38Z

1

Here's one way:

%myhash = ( 'key1' => [ 'key1value1', 'key1value2' ],
            'key2' => [ 'key2value1', 'key2value2' ],
            'key3' => [ 'key3value1', 'key3value2' ] );

for my $k (sort keys %myhash)
{
    print "$myhash{$k}->[0] $myhash{$k}->[1]\n";
}

If the number of array elements varies:

for my $k (sort keys %myhash)
{
    for my $v (@{$myhash{$k}})
    {
        print "$v ";
    }
    print "\n";
}

answered Oct 7, 2016 at 16:00

Jim Garrison

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4 Comments

Steve Over a year ago

Exactly what I wanted... even when the number of array elements varies. Thank you very much!

Jim Garrison Over a year ago

Please do not post "thank you" comments. You express thanks by upvoting helpful answers and accepting the one that solves your problem (which you've already done). You should take the tour, visit the help center and read How to Ask.

Gilles Quénot Over a year ago

He have 56k, I think he knows this ^^

Jim Garrison Over a year ago

No, the OP has 18

Gilles Quénot · Accepted Answer · 2016-10-07 16:13:54Z

1

Another solution :

print map {  join(" ", @{ $myhash{$_} }, "\n") } sort keys %myhash;

(the concise way)

answered Oct 7, 2016 at 16:13

Gilles Quénot

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