Hi Mike,
On Wednesday 13 October 2010 06:39:03 Mike McClain wrote:
> I've looked at this for a few days but still can't see 'why'
> I get what I do.
> Why do @arrays and @seconds not have the same number of elements?
> Thanks,
> Mike
>
Reformatting due to my mailer's limitations:
> #!/usr/bin/perl
>
> use strict;
> use warnings;
>
> {
>
> my %HoAoA =
> (
>
> a => [ [ qw / aa1 aa2 / ], [ qw / ab1 ab2 / ] ],
> b => [ [ qw / ba1 ba2 / ], [ qw / bb1 bb2 / ], [ qw / bc1 bc2 / ]
> ],
>
> );
>
> # this gets refs to all arrays
> my @arrays =
>
> map
> { @{ $HoAoA{$_} } [ 0..$#{ $HoAoA{$_} } ] }
> keys %HoAoA ;
>
This is equivalent to:
{{{
map { @{$HoAoA{$_} } } keys(%HoAoA);
}}}
Which flattens all the arrays into one big list. It can be written better as:
map { @$_ } values(%HoAoA);
> # this only gets the second entry from the last array of each hash
> # entry
>
> my @seconds =
>
> map
> { @{ $HoAoA{$_} } [ 0..$#{ $HoAoA{$_} } ]->[1] }
> keys %HoAoA ;
>
That's wrong. What it does is create an array, evaluate it in scalar context
and then trying to use it as an array refand extract the second element. Doing
@{$array_re...@indices]->[$idx] is a strange construct which makes no sense.
What you want based on your comment is :
[code]
map { $_->[-1]->[1] } values(%HoAoA);
[/code]
Regards,
Shlomi Fish
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