APM: Sparse arrays
Wayne Walker
wwalker at broadq.com
Thu Jul 10 11:30:07 CDT 2003
On Thu, Jul 10, 2003 at 08:00:44AM -0500, Brian Michalk wrote:
> Let's say I have a sparse array:
> $ary[100]=1;
> $ary[100000]=2;
> $ary[1000000]=3;
>
> Now, I want to iterate over the array, either from lowest to highest array
> index, and still retain the index of the element returned. How do I do
> that?
$ary[100]=1;
push @used_elements, 100;
$ary[100000]=2;
push @used_elements, 100000;
$ary[1000000]=3;
push @used_elements, 1000000;
foreach $used_element (sort @used_elements)
{
do_sumthin($ary($used_element));
}
> foreach $elt (@ary) {
> $some_value = $elt;
> $the_index = ????????; # how do I get this information?
> }
>
>
> This algorithm is chewing up CPU time, causing the process to take days to
> complete... the dataset is several gigabytes large.
>
> Using a hash, and sorting the keys will not give me a performance benefit.
>
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Wayne Walker
www.broadq.com :) Bringing digital video and audio to the living room
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