On 08/22/2012 10:34 PM, Eduardo wrote:
> On 22/08/12 03:49, Uri Guttman wrote:
>> On 08/21/2012 08:29 PM, Eduardo wrote:
>>> how would you do with Sort::Maker?
>> i don't have time to show an example now but it is much cleaner
>> looking. all you need to do is code up how you extract each key from
>> the data set and how it gets sorted (number vs string, etc.). it makes
>> sorting into a declarative problem instead of a coding problem.
>>
>> uri
>
> do'nt worry, that's what I'm
>
> Thanks a lot for forcing me to study sorting in perl.
>
> This morning I read sort_paper[*] apparently written by someone expert
> with the subject, and also Chapter 2 item 22 Effective perl, to get an
> overview.
>
> After that I have a vague idea and got this code:
>
> my @sorted = map { $_->[0] }
> sort { $a->[1] <=> $b->[1] }
> map { [ $_, /^(\d+)-(\d+)/ && ($1 * 100 + $2) ] }
> keys %$hash;
>
> Tonight I reread the Sort::Maker manual, now I understand and I was able
> to create this code:
>
> my $sorted = make_sorter( name => 'sort_func',
> orcish => 1,
> number => '/^(\d+)-(\d+)/ && ($1 * 100 + $2)'
> that generate this:
>
> sub {
>
> my ( %or_cache1 ) ;
>
>
> sort {
> (
> ( $or_cache1{$a} ||=
> do{ my ($val) = map { /^(\d+)-(\d+)/ && ($1 * 100 + $2) } $a ;
> $val } )
> <=>
> ( $or_cache1{$b} ||=
> do{ my ($val) = map { /^(\d+)-(\d+)/ && ($1 * 100 + $2) } $b ;
> $val } )
> )
>
> } @_ ;
> }
>
>
> I did not think that I obtained so high performance in a short time, I
> just subscribe to the list.
>
> It's a pity Sort::Maker not in Debian
There is also Sort::Key, available in Debian testing and unstable, and
which is usually faster than Sort::Maker and also Sort::Key::Radix, even
faster when sorting by numeric keys but not available in Debian.
use Sort::Key qw(ukeysort);
my @sorted = ukeysort { /^(\d+)-(\d+)/
or die "bad key $_";
$1 * 100 + $2 } @data;
The 'u' prefix in 'ukeysort' specifies that the sorting key is an
unsigned integer.
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