How to sort by value from a second level hash in Perl?
4 answers
@sorted_list
- an array of references to sorted hash elements:
@sorted_list = sort { $a->{'val'} <=> $b->{'val'} } values %{$unsorted_hash_ref};
You can use it like this:
#!/usr/bin/perl
my $hash_ref = {
one => { val => 1, name => 'one' },
three => { val => 3, name => 'three' },
two => { val => 2, name => 'two' },
};
foreach $elem ( sort { $a->{'val'} <=> $b->{'val'} } values %{$hash_ref} ) {
print "$elem->{'val'} : $elem->{'name'}\n";
}
Output:
1 : one
2 : two
3 : three
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There is no specific order in hash tables. However, you can sort the keys in an array and use them to iterate through the hash:
my $hash_ref = {
one => { val => 1, name => 'one'},
three => { val => 3, name => 'three'},
two => { val => 2, name => 'two'},
};
use strict;
use warnings;
use Lingua::EN::Words2Nums;
foreach my $key (sort { words2nums($a) <=> words2nums($b) } keys %$hash_ref)
{
# do something with $hash_ref->{$key}
print "processing key $key.\n";
}
You can define whatever you like as the sorting method; see perldoc -f sort for details . Conversion from ordinal numeric text to arithmetic values is done with Lingua :: EN :: Words2Nums (these are also cardinal numbers).
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use strict;
use warnings;
my %hash_ref = (
one => { val => 1, name => 'one' },
three => { val => 3, name => 'three'},
two => { val => 2, name => 'two' },
);
foreach my $key(sort {$hash_ref{$a}{val} <=> $hash_ref{$b}{val}} keys %hash_ref) {
my $value = $hash_ref{$key}{val};
my $name = $hash_ref{$key}{name};
print "$name -> $value\n";
}
output:
one -> 1
two -> 2
three -> 3
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#!/usr/bin/perl
my $hash_ref = (
one => {val => 1, name => "one"},
three => {val => 3, name => "three"},
two => {val => 2, name => 'two'},
);
foreach $elem( sort {$$hash_ref{$a}{val} <=> $$hash_ref{$b}{val}} keys %$hash_ref){
my $value = $hash_ref->{$elem}{val};
my $name = $hash_ref->{$elem}{name};
print "$name -> $value\n";
}
OutPut:
one -> 1
two -> 2
three -> 3
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