Hi Uri!
Some notes.
On Wed, 12 Apr 2017 15:19:33 -0400
Uri Guttman <u...@stemsystems.com> wrote:
> On 04/12/2017 03:00 PM, David Emanuel da Costa Santiago wrote:
> > Hello!
> >
> > What's the best way to delete multiple indices from an array?
> >
> > i'm doing:
> >
> > ---------------
> > my @array=qw/zero one two three four five six seven eight nine ten/;
> >
> > my @indicesToDelete = (2,4,6,7);
>
> if you have the indexes to keep, this would be a simple slice:
>
> my @keep_indexes = ( 0, 1, 3, 5, 8,9 10 );
> @array = @array{ @keep_indexes } ;
>
it should be «@array = @array[ @keep_indexes ] ;» instead. With curly braces
it's a hash slice.
> so one idea is to make that list of kept indexes from the list of
> indexes to delete:
>
> my %keep_hash ;
> @keep_hash{ 0 .. 10 } = () ; # no need for any values so this save space
> delete @keep_hash{ @keep_indexes } ;
> @array = @array{ keys %keep_hash } ;
1. again - square brackets instead of curly braces.
2. You should sort the keys numerically using sort { $a <=> $b }.
3. Better use « keys@array» or in older perls «0 .. $#array» to avoid hard
coding the values and magic constants.
============
some other ways I can think of doing it:
1.
my %blacklist;
@blacklist{@remove} = ();
@array = @array[grep {!exists $blacklist{$_} } keys@array];
2.
my @new;
while (my ($i, $v) = each@array)
{
if (@remove and $i == $remove[0])
{
shift@remove;
}
else
{
push @new, $v;
}
}
@array = @new
===========
https://en.wikipedia.org/wiki/There%27s_more_than_one_way_to_do_it
Regards,
Shlomi Fish
> >
> > my %hash;
> >
> > @hash{(0..scalar(@array)-1)} = @array;
> >
> > delete $hash{$_} for @indicesToDelete;
> delete can be used on a slice
>
> delete @hash{ @indicesToDelete } ;
>
> uri
>
> Perl Guru for hire. Available for contract/full time/part time Perl hacking.
>
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