How can sort timestamps in dd:mm:yyyy hh24:mi:ss format in descending order in Perl?

Question

I have to sort my hash keys which is a timestamp (dd:mm:yyyy hh24:mi:ss) in descending order.

sort { $b <=> $a } keys %time_spercent

this way is not getting me what I intend to do. Rather this ends in sorting with the higher hours and minutes first even though the date is not so. For example, this is how I get when I do the sorting as I have mentioned.

21:01:2011 16:51:09
21:01:2011 16:49:54
26:01:2011 11:02:55
26:01:2011 11:01:40
05:04:2011 11:51:13
05:04:2011 11:51:13
05:04:2011 11:48:37
05:04:2011 11:48:37

Rather I want them in this order arranged both by date as well as in time.

05:04:2011 11:51:13
05:04:2011 11:51:13
05:04:2011 11:48:37
26:01:2011 11:02:55
26:01:2011 11:01:40
05:04:2011 11:48:37
21:01:2011 16:51:09
21:01:2011 16:49:54

Any pointers are suggestion on how this could be done would be gratefully received.

Update

foreach my $status_date( 
     map  { $_->[0] }
     sort { $b->[1] cmp $a->[1] }
     map  { [$_, sorting_desc($_)] } keys % {$com_sam->{ $s1 } } ) 

and

sub sorting_desc {
    $_ = shift;
    if (/(\d+):(\d+):(\d+) (\d+):(\d+):(\d+)/) {
        return "$2:$1:$3:$4:$5:$6";
    }
}

is the subroutine for sorting.

I also tried

foreach my $status_date( 
    map  { $_->[0] }
    sort { $b->[1] cmp $a->[1] }
    map { [$_, (split/[:\s][1]] } keys % {$com_sam->{ $s1 } } )

but not the expected results.

All I get is:

WGA_PD7124a WGA_PD7124a     95(2)   95(2)   95      100.00  193     Unknown(Unknown)        192654  01:07:2011 16:13:55
WGA_PD7124a     WGA_PD7124a     95(2)   95(2)   95      100.00  193     Unknown(Unknown)        192655  01:07:2011 16:11:23
WGA_PD7124a     WGA_PD7124a     95(2)   95(2)   95      100.00  193     Male(Unknown)   192656  01:07:2011 11:04:26
WGA_PD6355b     WGA_PD6355b     96(1)   96(1)   96      100.00  388     Unknown(Unknown)        184558  04:05:2011 17:35:52
WGA_PD6355b     WGA_PD6355a     96(1)   66(31)  66      95.45   388     Unknown(Unknown)        184558  04:05:2011 17:35:52
WGA_PD6355b     WGA_PD6355b     96(1)   96(1)   96      100.00  388     Unknown(Unknown)        184557  04:05:2011 17:34:27
WGA_PD6355b     WGA_PD6355a     96(1)   66(31)  66      95.45   388     Unknown(Unknown)        184557  04:05:2011 17:34:27
3074    3074    87(10)  87(10)  87      100.00  109     Unknown(Unknown)        174878  15:02:2011 09:24:31
3074    3074    87(10)  87(10)  87      100.00  109     Unknown(Unknown)        174970  15:02:2011 09:21:19
3074    3074    87(10)  87(10)  87      100.00  109     Female(Unknown) 174860  15:02:2011 09:16:32
3163    3163    90(7)   90(7)   90      100.00  176     Unknown(Unknown)        173382  09:02:2011 09:54:48
3163    3163    90(7)   90(7)   90      100.00  176     Unknown(Unknown)        173284  09:02:2011 09:51:02
CHP-212 CHP-212 94(3)   94(3)   94      100.00  269     Unknown(Unknown)        173382  09:02:2011 09:54:48
CHP-212 CHP-212 94(3)   94(3)   94      100.00  269     Unknown(Unknown)        173284  09:02:2011 09:51:02
MGH_2631        MGH_2631        90(8)   90(8)   90      100.00  211     Male(Unknown)   200943  01:09:2011 10:48:18
MGH_2631        MGH_2631        90(8)   90(8)   90      100.00  211     Unknown(Unknown)        200944  25:08:2011 10:20:16
MGH_2631        MGH_2631        90(8)   90(8)   90      100.00  211     Unknown(Unknown)        200945  25:08:2011 10:19:05
MGH_2631        MGH_2631        90(8)   90(8)   90      100.00  211     Male(Unknown)   200946  25:08:2011 10:17:26
MGH_2101        MGH_2101        80(18)  80(18)  80      100.00  359     Male(Unknown)   200943  01:09:2011 10:48:18
MGH_2101        MGH_2101        80(18)  80(18)  80      100.00  359     Unknown(Unknown)        200944  25:08:2011 10:20:16
MGH_2101        MGH_2101        80(18)  80(18)  80      100.00  359     Unknown(Unknown)        200945  25:08:2011 10:19:05
MGH_2101        MGH_2101        80(18)  80(18)  80      100.00  359     Male(Unknown)   200946  25:08:2011 10:17:26
PD4294c PD4294c 95(2)   95(2)   95      100.00  221     Unknown(Unknown)        179502  23:03:2011 10:03:23
PD4294c PD4294c 95(2)   95(2)   95      100.00  221     Unknown(Unknown)        179470  23:03:2011 10:02:30

Answer 1

Can you change your format to yyyy:mm:dd hh24:mi:ss? At that point you'd have a natural ordering. Basically it's a lot more machine-friendly to have everything in decreasing order of importance :)

EDIT: Then just order using string comparisons, as it will naturally sort the right way.