I have a beginner question:
I have an @key_table and many @values_tables. I want to create a @table of references to hashes, so there is one table, each element points to hash with keys&values from those 2 tables presented at the beginning.
For example:
@keys = (Kate, Peter, John);
@value1 = (1, 2, 3);
@value2 = (a, b, c);
and I want a two-element table that point to:
%hash1 = (Kate=>1, Peter=>2, John=>3);
%hash2 = (Kate=>a, Peter=>b, John=>c);
If you just want to create two hashes, it's really easy:
my ( %hash1, %hash2 );
@hash1{ @keys } = @value1;
@hash2{ @keys } = @value2;
This takes advantage of hash slices.
However, it's usually a mistake to make a bunch of new variables with numbers stuck on the end. If you want this information all together in one structure, you can create nested hashes with references.
Using hash slice is most common way to populate hash with keys/values,
@hash1{@keys} = @value1;
@hash2{@keys} = @value2;
but it could be done in other (less efficient) way using ie. map,
my %hash1 = map { $keys[$_] => $value1[$_] } 0 .. $#keys;
my %hash2 = map { $keys[$_] => $value2[$_] } 0 .. $#keys;
or even foreach
$hash1{ $keys[$_] } = $value1[$_] for 0 .. $#keys;
$hash2{ $keys[$_] } = $value2[$_] for 0 .. $#keys;
This is an example:
use strict;
use warnings;
use Data::Dump;
#Example data
my @key_table = qw/Kate Peter John/;
my @values_tables = (
[qw/1 2 3/],
[qw/a b c/]
);
my @table;
for my $vt(@values_tables) {
my %temph;
@temph{ @key_table } = @$vt;
push @table, \%temph;
}
dd(@table);
#<--- prints:
#(
# { John => 3, Kate => 1, Peter => 2 },
# { John => "c", Kate => "a", Peter => "b" },
#)
This will do it:
use Data::Dumper;
use strict;
my @keys = ("Kate", "Peter", "John");
my @value1 = (1, 2, 3);
my @value2 = ("a", "b", "c");
my (%hash1,%hash2);
for my $i (0 .. $#keys){
$hash1{$keys[$i]}=$value1[$i];
$hash2{$keys[$i]}=$value2[$i];
}
print Dumper(\%hash1);
print Dumper(\%hash2);
This is the output:
$VAR1 = {
'John' => 3,
'Kate' => 1,
'Peter' => 2
};
$VAR1 = {
'John' => 'c',
'Kate' => 'a',
'Peter' => 'b'
};
strict: The a, b, c are not quoted. C-style loops? Explicit scalar? Really? → for my $i (0 .. $#keys) {...}. Well, at least you declared all your variables … (I know this comment is unneccessarily snarky, but this is simply not the kind of Perl I would want to teach)
