Re: Sorting Dates Issue

Your idea of extracting year, month and day then concatenating them so they sort naturally is fine. You could take it a little further and apply a Guttman Rosler Transform instead of a sort routine. This node has an explanation and this is the paper on the technique. I think split might be an easier way of extracting date elements than a regex.

knoppix@Microknoppix:~$ perl -E '
> @dates = qw{
>    10/02/2004
>    02/01/2004
>    01/02/2004
>    01/06/2004
>    01/02/2005
>    01/12/2004
>    08/18/2010
>    };
> say for
>    map { substr $_, 8 }
>    sort
>    map { join q{}, ( split m{/} )[ 2, 0, 1 ], $_ }
>    @dates;'
01/02/2004
01/06/2004
01/12/2004
02/01/2004
10/02/2004
01/02/2005
08/18/2010
knoppix@Microknoppix:~$
[download]

I hope this is of interest.

Cheers,

JohnGG

Comment on Re: Sorting Dates Issue Download Code

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Re^2: Sorting Dates Issue by Anonymous Monk on Aug 18, 2010 at 17:54 UTC
Yes it works, how could this code do the sorting in reverse, I mean the most recent date on top? `use strict; my @dates = qw{ 10/02/2004 02/01/2004 01/02/2004 08/18/2010 01/06/2004 01/02/2005 01/12/2004 }; my @sorted= map { substr $_, 8 } sort map { join q{}, ( split m{/} )[ 2, 0, 1 ], $_ }@dates;` [download] Thanks!	[reply] [d/l]
Re^3: Sorting Dates Issue by johngg (Canon) on Aug 18, 2010 at 22:54 UTC
Once the elements to be sorted have been combined into a single string it is just a lexical sort so you can use a simple anonymous routine to reverse the order. `knoppix@Microknoppix:~$ perl -E ' > @dates = qw{ > 10/02/2004 > 02/01/2004 > 01/02/2004 > 01/06/2004 > 01/02/2005 > 01/12/2004 > 08/18/2010 > }; > say for > map { substr $_, 8 } > sort { $b cmp $a } > map { join q{}, ( split m{/} )[ 2, 0, 1 ], $_ } > @dates;' 08/18/2010 01/02/2005 10/02/2004 02/01/2004 01/12/2004 01/06/2004 01/02/2004 knoppix@Microknoppix:~$` [download] Cheers, JohnGG	[reply] [d/l]