Re: [MacPerl] efficiency & memory

[Carl Johan Berglund <carl.johan.berglund@adverb.se>]

At 16.57 +0200 98-08-21, Mark Manning/Muniz Eng. wrote:
>> Probably not. This is just an alternative way of sorting, where you sort
>> the array indices and then rearrange the array by taking a same-length
>> slice of it.
>
>That is very strange.  :-)  I had never heard of that before.  What I
>thought was happening was that it would sort the numbers between zero
>and $#id.  Which meant that they would go 0, 1, 2, 3, etc....  Perl is
>weirder than I thought!  :-)

If you say

sort 0..$#ids

you will get the numbers 0, 1, 2, 3, etc in ascending order, and hence get
them in the order they were from the beginning. However, if you say

sort byID 0..$#ids

the order depends on the byID sorting subrouitine. In Nathaniel's code,
byID was:

sub byID {
    $ids[$a] <=> $ids[$b];
}

This thing compares not the numbers themselves, but elements in @ids array.
If $ids[1] < $ids[0], 1 will come before 0 in the array that is sorted this
way.

Any clearer?

Cajo.


___Carl_Johan_Berglund_________________________
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   carl.johan.berglund@adverb.se
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