Re: Remove array elements dynamically!

If your indexes are sorted, you could keep a separate counter for the number of items removed and subtract it from $i when splicing.

However, it's much easier and more efficient to create a new array instead of splicing the same array, since each splice needs to ~~copy all the elements from $i to the end of the array~~ rearrange/copy the pointers to the elements from element $i to the end of the array.

my @newarray;
foreach my $i (@arrayindex) {
   push @newarray,$array[$i];
}
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Depending on your algorithm, you could probably do that at the same time/instead of building the @arrayindex array.

Another way would be to use grep (if you can determine which elements to keep based solely on their value):

my @kept = grep { $_ < 4 and $_ > 10 } @array;
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or even

@array = grep { $_ < 4 and $_ > 10 } @array;
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"What should it profit a man, if he should win a flame war, yet lose his cool?"

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Re^2: Remove array elements dynamically! by shmem (Chancellor) on Aug 27, 2007 at 19:59 UTC
... since each splice needs to copy all the elements from $i to the end of the array. Is that so? I always thought of splice being highly efficient, working "in-place", just "re-arranging elements", without need to copy anything. Can you ascertain your statement? --shmem _($_=" "x(1<<5)."?\n".q·/)Oo. G°\ / /\_¯/(q / ---------------------------- \__(m.====·.(_("always off the crowd"))."· ");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}	[reply]
Re^3: Remove array elements dynamically! by Joost (Canon) on Aug 27, 2007 at 20:11 UTC
My bad, I should have been a little more careful. Perl arrays are just c-style arrays of pointers. That means perl needs to re-arrange the pointers after each splice. "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply]
Re^2: Remove array elements dynamically! by suaveant (Parson) on Aug 28, 2007 at 20:21 UTC
Ummm... you do realize that, while a valid example, nothing can ever be less than 4 AND greater than 10? `array = grep { $_ > 4 and $_ < 10 } @array;` [download] - Ant - Some of my best work - (1 2 3)	[reply] [d/l]
Re^3: Remove array elements dynamically! by Joost (Canon) on Aug 28, 2007 at 20:23 UTC
No I did not notice that :-) "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply]
Re^2: Remove array elements dynamically! by newbio (Beadle) on Aug 27, 2007 at 20:05 UTC
`Thank you Joost. I am interested in the array that is left after removing/splicing out +the indices (defined in @arrayindex) from @array. But, I have got an idea from your hint. Let's see. Thanks.` [download]	[reply] [d/l]