Adding an element of an array as a key for a Hash, and remaining elements as its value (would also be a hash)

abhiram10 has asked for the wisdom of the Perl Monks concerning the following question:

Dear Monks,

I have a set of data already in a hash and I have an array separated with a ":" and a tab space. I want to add this array as a hash to my master hash, whose key is an element from the array. Here is what I have tried:

use strict;
use warnings;

my %MasterHash;
my $line = "k1:v1  k2:v2   k3:v3"; #the space is a tab

##some part of code that writes stuff to MasterHash
....

my @array1 = split (/\t/,$line);
my ( $index )= grep { $array1[$_] =~ /v3/ } 0..$#array1;
my $mv = splice @array1, $index,1;
print "after removing: $mv\n";
my ($mvl,$mvr) = split (/:/,$mv,2);
$MasterHash{$mvr} = map { split /:/; } @array1;

print Dumper \%MasterHash;
[download]

What output I get:

$Var1 = {
          'abc' => 'loaded before',
          'xyz' => 'loaded before',
          'v3'  => 16       #basically some number
        };
[download]

What I expected:

$Var1 = {
          'abc' => 'loaded before',
          'xyz' => 'loaded before',
          'v3'  => {
                     'k1' => 'v1',
                     'k2' => 'v2'
                   } 
        };
[download]

Can anyone help me understand what I did wrong?

Also, if there is a cleaner way to achieve this goal of mine, please let me know, Would love to learn and it will be greatly appreciated!

Thanks in Advance

Abhi

Comment on Adding an element of an array as a key for a Hash, and remaining elements as its value (would also be a hash) Select or Download Code

Replies are listed 'Best First'.
Re: Adding an element of an array as a key for a Hash, and remaining elements as its value (would also be a hash) by Anonymous Monk on Apr 12, 2016 at 02:04 UTC
wild guess `$MasterHash{$mvr} = { map { split /:/; } @array1 };` [download]	[reply] [d/l]
Re^2: Adding an element of an array as a key for a Hash, and remaining elements as its value (would also be a hash) by abhiram10 (Initiate) on Apr 12, 2016 at 02:16 UTC
Thank you Monk! That totally worked. I guess I should have tried the curly braces! Thank you very much for pointing out. This really helps! The next question I have is how did this work and not the one I tried ? Could you please explain to me? There is something that I have to learn about these braces	[reply]
Re^3: Adding an element of an array as a key for a Hash, and remaining elements as its value (would also be a hash) by AnomalousMonk (Archbishop) on Apr 12, 2016 at 02:37 UTC
... something that I have to learn about these braces `$MasterHash{$mvr} = { map { split /:/; } @array1 };` `^ ^ ^ ^` `\| \| \| \|` `\| + sub block + \|` `\| \|` `+ anon hash ref constructor +` See perlref for anonymous reference constructors (in particular, Making References section 3 for the anon hash ref constructor) and also perlreftut. See map for the function of the sub(routine) block. Give a man a fish: `<%-{-{-{-<`	[reply] [d/l] [select]
Re^4: Adding an element of an array as a key for a Hash, and remaining elements as its value (would also be a hash) by abhiram10 (Initiate) on Apr 12, 2016 at 03:21 UTC
Re^3: Adding an element of an array as a key for a Hash, and remaining elements as its value (would also be a hash) by Anonymous Monk on Apr 12, 2016 at 02:44 UTC
also map in scalar context produces a count of the number of elements instead of the list of elements	[reply]
Re: Adding an element of an array as a key for a Hash, and remaining elements as its value (would also be a hash) by Anonymous Monk on Apr 12, 2016 at 02:16 UTC
`#!/usr/bin/perl -- use strict; use warnings; use Data::Dump qw/ dd /; my $line = "k1:v1 k2:v2 k3:v3"; my %pairs; while( $line =~ m{\b([^:\s]+):([^:\s]+)\b}g ){ my( $k, $v ) = ( $1, $2 ); $pairs{$k}=$v; } dd( \%pairs ); if( delete $pairs{'k3'} ){ %pairs = ( k3 => { %pairs } ); } dd( \%pairs ); __END__ { k1 => "v1", k2 => "v2", k3 => "v3" } { k3 => { k1 => "v1", k2 => "v2" } }` [download]	[reply] [d/l]