Sort hash attending to two parameters - perl

Question

I have a hash with the keys in the following format:
scaffold_902_159
scaffold_2_1980420
scaffold_2_10
scaffold_10_402
I want to print out the hash sorted in the following format:
scaffold_2_10
scaffold_2_1980420
scaffold_10_402
scaffold_902_159
So first I have to order numerically attending to the first number and then attending to the last one. I don't want a regular expression searching for "scaffold_" since this may vary. I mean, I can have the hash with other format like "blablabla_NUMBER_NUMBER, or blablablaNUMBER_NUMBER". The last part of the key _NUMBER, is the only thing that is permanent.
I've this code but only sorts numerically attending to the first number:
my #keys = sort {
my ($aa) = $a =~ /(\d+)/;
my ($bb) = $b =~ /(\d+)/;
$aa <=> $bb;
} keys %hash;
foreach my $key (#keys) {
print $key;
}
Any suggestion?

Answer 1

Sort::Naturally to the rescue!
#!/usr/bin/perl
use strict;
use warnings;
use Sort::Naturally qw(nsort);
my %hash = (
scaffold_902_159 => 'v1',
scaffold_2_1980420 => 'v2',
scaffold_2_10 => 'v3',
scaffold_10_402 => 'v4',
);
print "$_\n" for nsort keys %hash;
Output:
scaffold_2_10
scaffold_2_1980420
scaffold_10_402
scaffold_902_159
As per your query, tried out some keys which did not have number in middle.
#!/usr/bin/perl
use strict;
use warnings;
use Sort::Naturally qw(nsort);
my #keys = qw(
should_come_last_9999_0
blablabla_10_403
scaffold_902_159
scaffold_2_1980420
scaffold_2_10
scaffold_10_402
blablabla902_1
blablabla901_3
);
print "$_\n" for nsort #keys;
Output:
blablabla_10_403
blablabla901_3
blablabla902_1
scaffold_2_10
scaffold_2_1980420
scaffold_10_402
scaffold_902_159
should_come_last_9999_0

Answer 2

This sorts on two columns, and uses the Schwartzian transform to create those columns from your strings.
use strict;
use warnings;
use feature 'say';
my #keys = qw(
scaffold_902_159
scaffold_2_1980420
scaffold_2_10
scaffold_10_402
);
#keys =
map { $_->[0] } # transform back
sort { $a->[1] <=> $b->[1] || $a->[2] <=> $b->[2] } # sort
map { # transform
m/(\d+)(?:\D+(\d+))/;
[ $_, ( defined $2 ? ( $1, $2 ) : ( 0xffffffff, $1 ) ) ]
} #keys;
say for #keys;
Output:
scaffold_2_10
scaffold_2_1980420
scaffold_10_402
scaffold_902_159
The data structure returned by the initial transformation map looks like this:
[ 'scaffold_902_159', 902, 159 ]
The sort uses that to first sort by index 1 (the 902) above with the numerical sort <=>. That operator returns 0 if both the RHS and the LHS are equal, so the or || continues with the right expression, It then sorts on index 2 (the 159).
Because you said the first number is optional, and if only the second number is there those elements should come last, we have to substitute a very high number for that. Without going into 64bit integers, 0xffffffff is the highest number we can make.
The second map pulls the full key out of index 0 of the array reference.
If we add some other things to the input, like the blablablaNUMBER_NUMBER you suggested, it will still only sort on the numbers and ignore the string part completely.
my #keys = qw(
should_come_last_9999_0
blablabla_10_403
scaffold_902_159
scaffold_2_1980420
scaffold_2_10
scaffold_10_402
no_first_number_1
);
Here's the output:
scaffold_2_10
scaffold_2_1980420
scaffold_10_402
blablabla_10_403
blablabla902_1
scaffold_902_159
should_come_last_9999_0
no_first_number_1