How to change an Array to a Hash

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

Whats the easiest way for me to change this array of alternating keys and values to a hash using a loop? In other words, I want Andy, Sarah, Sam to be the keys, and 1995, 1990, 1992 to be the corresponding values. And then organize it based on the values (highest first). I couldn't figure out the loop to sort them but I tried to write a code to organize them...

 
%people = ();
@list= ("Andy", "1995", "Sarah", "1990", "Sam", "1992"); 

$list[0]=keys %people; 
$list[1]=values people; 

print "sorting keys by value:\n"; 
foreach $name (sort {$people{$b}<=>$people{$a} }keys %people){ 
    print "brand: $name, points: $people{$name}\n"; 
}
[download]

Discipulus edited some tag and html formatting

Comment on How to change an Array to a Hash Download Code

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Re: How to change an Array to a Hash by vinoth.ree (Monsignor) on Aug 01, 2018 at 06:01 UTC
The easiest way to convert array to hash, `use strict; use warnings; use Data::Dumper; my @list= ("Andy", "1995", "Sarah", "1990", "Sam", "1992"); my %people = @list; print Dumper \%people;` [download] Output: $VAR1 = { 'Andy' => '1995', 'Sarah' => '1990', 'Sam' => '1992' }; *All is well. I learn by answering your questions...*	[reply] [d/l]
Re: How to change an Array to a Hash (updated) by Discipulus (Canon) on Aug 01, 2018 at 07:15 UTC
Hello alialialia, As already said you can feed a list to form an hash directly. But note venoth.ree added `use warnings` (and `use strict` too: never miss them) infact if your list is odd you can trap some unwanted behaviour: `perl -we "my %hash = @ARGV" Andy 1995 Sarah 1990 Sam 1992 UNEXPECTED Odd number of elements in hash assignment at -e line 1.` [download] If you want to build the hash using a loop (ignoring odd element if present), you can use `while` as in: `@ARGV = qw( Andy 1995 Sarah 1990 Sam 1992 UNEXPECTED ); my %hash; while (my $key = shift @ARGV and my $val = shift @ARGV){ $hash{$key}=$val } # hash is: ("Sam", 1992, "Andy", 1995, "Sarah", 1990)` [download] UPDATE you can spot the odd element before entering the loop: `print qq(odd element $ARGV[-1] will be lost!\n) if @ARGV % 2 > 0;` though. If you want you can also explore `List::Util` `pairs` function: it warns on odd element assigning `undef` `use strict; use warnings; use List::Util qw(pairs); @ARGV= qw(Andy 1995 Sarah 1990 Sam 1992 UN); my %hash; for my $pairs (pairs @ARGV){ $hash{ $$pairs[0] } = $$pairs[1]; } Odd number of elements in pairs at -e line 1. # hash is: ("Sarah", 1990, "Andy", 1995, "UN", undef, "Sam", 1992)` [download] L* There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l] [select]
Re: How to change an Array to a Hash by Laurent_R (Canon) on Aug 01, 2018 at 07:19 UTC
Hi alialialia, vinoth.ree has provided an easy and good solution. But it might be even simpler to assign directly the list to the hash: `my %people = ("Andy", "1995", "Sarah", "1990", "Sam", "1992");` [download]	[reply] [d/l]