Build hash of hashes from a single hash - perl

Question

I have the following hash
my %input_hash = (
'test1' => '100',
'test2' => '200',
'test3' => '300',
'test4' => '400',
'test5' => '500'
);
What I need is to build a hash of hash from the above hash. I need to put the first 2 of the above key value pair into a key of the hash of hash. Better explained with this example.
Desired output:
my %expected_hash = (
1 => {
'test1' => '100',
'test2' => '200',
},
2 => {
'test3' => '300',
'test4' => '400',
},
3 => {
'test5' => '500'
},
);
I would like the split to be dynamic. Example,if i need to split by 3, the desired output should be
my %expected_hash = (
1 => {
'test1' => '100',
'test2' => '200',
'test3' => '300',
},
2 => {
'test4' => '400',
'test5' => '500'
},
);

Answer 1

Here's a version that uses splice to get a dynamic number of elements. Note that you have to sort the keys in the hash, because hashes are unordered.
use strict;
use warnings;
use Data::Dumper;
my %input_hash = (
'test1' => '100',
'test2' => '200',
'test3' => '300',
'test4' => '400',
'test5' => '500',
'test6' => '600',
'test7' => '700',
'test8' => '800',
'test9' => '900'
);
my $foo = foo(\%input_hash, 4);
print Dumper $foo;
sub foo {
my ($href, $count) = #_;
my #keys = sort keys %$href;
my %hash;
my $i = 1;
while (#keys) {
$hash{$i++} = { map { $_ => $href->{$_} }
splice #keys, 0, $count };
}
return \%hash;
}
Output:
$VAR1 = {
'1' => {
'test1' => '100',
'test4' => '400',
'test3' => '300',
'test2' => '200'
},
'3' => {
'test9' => '900'
},
'2' => {
'test8' => '800',
'test5' => '500',
'test7' => '700',
'test6' => '600'
}
};

Answer 2

Here's a solution using an index array built from number of keys in %input_hash and desired size set in $chunk_size:
#!/usr/bin/env perl
use strict;
use warnings;
use Data::Dumper;
my %input_hash = (
'test1' => '100',
'test2' => '200',
'test3' => '300',
'test4' => '400',
'test5' => '500'
);
my $chunk_size = 2;
my #indexes = map {int($_ / $chunk_size) + 1} 0 .. keys %input_hash;
my %expected_hash;
for my $key (sort keys %input_hash) {
my $index = shift #indexes;
$expected_hash{$index}{$key} = $input_hash{$key};
}
print Dumper \%expected_hash;
Output:
$VAR1 = {
'1' => {
'test1' => '100',
'test2' => '200'
},
'3' => {
'test5' => '500'
},
'2' => {
'test4' => '400',
'test3' => '300'
}
};
Of course, as TLP mentioned, you have to sort %input_hash to achieve this.

Answer 3

#! /usr/bin/perl -w
use strict;
my ($expected_hash_key, $cnt, $L1, $L2) = (1, 1, "", "");
my %expected_hash;
# Change $LIMIT to required value. 2 or 3.
my $LIMIT = 2;
my %input_hash = (
'test1' => '100',
'test2' => '200',
'test3' => '300',
'test4' => '400',
'test5' => '500'
);
for (sort keys %input_hash) {
$cnt++;
$expected_hash{$expected_hash_key}{$_} = $input_hash{$_};
if ($cnt == $LIMIT + 1) {
$cnt = 1;
$expected_hash_key++;
}
}
for $L1 (sort keys %expected_hash) {
print "$L1 ==> \n";
for $L2 (sort keys %{ $expected_hash{$L1} }) {
print "$L2 -> $expected_hash{$L1}{$L2}\n";
}
print "\n";
}