I am not sure I understand what you require, but if it is "How might I sort the keys or values of a hash by the index in the
@cols array of the value of the hash element", then it is necessary to first make a mapping of the elements of the
@cols array to their indices: another hash.
Once you have the element-to-index mapping of the array, it is straightforward to sort the keys or values of the original hash by these indices.
>perl -wMstrict -le
"my @cols = qw(bar wobble mosh hop);
my %hash = (
wibble => $cols[1],
foo => $cols[0],
hip => $cols[3],
mish => $cols[2],
);
my %i_map = map { $cols[$_] => $_ } 0 .. $#cols;
print
join ' ',
qq{keys sorted by \@cols index of value: \n},
sort { $i_map{ $hash{$a} } <=> $i_map{ $hash{$b} } }
keys %hash
;
print
join ' ',
qq{values sorted by \@cols index of value: \n},
sort { $i_map{$a} <=> $i_map{$b} }
values %hash
;
"
keys sorted by @cols index of value:
foo wibble mish hip
values sorted by @cols index of value:
bar wobble mosh hop
The preceding assumes that every value of the hash is an element of the array; it would be wise to validate this assumption.
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