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Find if Hash Value exists in Hash of Arrays

Find if Hash Value exists in Hash of Arrays

Find if Hash Value exists in Hash of Arrays

(OP)
Hi there,

If I have a Hash of Arrays, how to you find out if a value exists for a given key.

CODE

use Data::Dumper;

#populate hash
foreach (1 .. 4) {
   push @{ $hash{key1} },  $_;
}

foreach (5 .. 9) {
   push @{ $hash{key2} },  $_;
} 
So if I wanted to find out if '1' exists in key1, how do I do that?

I've tried, if exists, grep, defined, searched this forum, can't get it to work etc

CODE

$var1 = 1;
my %reverse = reverse %hash;
if( defined( $reverse{$var1} ) ) {
  print "1 is a value in the hash!\n";
}
else {
 print "1 is not a value in the hash!\n";
} 

RE: Find if Hash Value exists in Hash of Arrays

CODE

foreach (1 .. 4) {
  push @{ $hash{key1} },  $_;
}

foreach (5 .. 9) {
  push @{ $hash{key2} },  $_;
}

$var1 = 1;
foreach $key (keys(%hash)) {
  for($i = 0; $i <= $#{$hash{$key}}; $i++) {
    if($var1 == $hash{$key}[$i]) {
      print "Found '$var1'! Key: $key, \$i = $i\n";
    }
  }
} 

Output:

CODE

Found '1'! Key: key1, $i = 0 

RE: Find if Hash Value exists in Hash of Arrays

(OP)
Thanks whn, I didn't make my question very clear in the first place. I should have said, if the value exists, then do nothing, if not adding the value to that key.

CODE

$VAR1 = {
          'key2' => [
                      5,
                      6,
                      7,
                      8,
                      9
                    ],
          'key1' => [
                      1,
                      2,
                      3,
                      4                      
                    ]
        }; 
So in the scenario above, key1 already has the value of '1', so no need to add. But if $var1 was 10, then it would need to be added.

My attempt at this has not been too successful

CODE

foreach (1 .. 4) {
  push @{ $hash{key1} },  $_;
}

foreach (5 .. 9) {
  push @{ $hash{key2} },  $_;
}

$var1 = "key1";
$var2 = 1;
foreach $key (keys(%hash)) {
  for($i = 0; $i <= $#{$hash{$key}}; $i++) {
    if($var2 == $hash{$key}[$i]) {      
	  print "Found $var1 doing nothing\n";	  	  
	  print "Found '$var1'! Key: $key, \$i = $i\n";
    }
	else{
		push @{ $hash{$var1} },  $var2;
		print "Adding $var2 to $var1\n";
	}
  }
} 

RE: Find if Hash Value exists in Hash of Arrays

For example:
stevio.pl

CODE

use strict;
#use warnings;

my $key = "";
my %lst_hash = ();

# populate hash
# key1
$key = 'key1';
my @lst = (1 .. 4);
# add reference of @lst
$lst_hash{$key} =  \@lst;

$key = 'key2';
my @lst = (5 .. 8);
# add reference of @lst
$lst_hash{$key} =  \@lst;

# print hash
print "Hash contains elements:\n";
print_hash();

$key = 'key1';
my $element = 3;
print "Trying to add element='$element' for key='$key':\n";
value2hash($key, $element);
print "Hash contains elements:\n";
print_hash();

$key = 'key2';
$element = 9;
print "Trying to add element='$element' for key='$key':\n";
value2hash($key, $element);
print "Hash contains elements:\n";
print_hash();


sub print_hash {
  # print hash
  foreach $key (sort keys(%lst_hash)){
    # dereference list
    my @tmp_lst = @{$lst_hash{$key}};
    print "'$key' => $lst_hash{$key} = (@tmp_lst)\n";
  }
  print "\n";
}

sub value2hash {
  # add value to hash if it doesn't exist
  my ($key, $val) = @_;
  # dereference list
  my @lst = @{$lst_hash{$key}};
  my $val_exist = 0;
  foreach my $j (@lst) {
     if ($j == $val) { 
      $val_exist = 1;
      last;
    }
  }

  if ($val_exist == 0) {
     push (@lst, $val) 
  }
  else {
    print "ERROR: For key = '$key' value $val already exists !\n";
  }
  # add reference of @lst
  $lst_hash{$key} =  \@lst;
} 

Output:

CODE

C:\_mikrom\Work>perl stevio.pl
Hash contains elements:
'key1' => ARRAY(0x29a28c) = (1 2 3 4)
'key2' => ARRAY(0x182c1ac) = (5 6 7 8)

Trying to add element='3' for key='key1':
ERROR: For key = 'key1' value 3 already exists !
Hash contains elements:
'key1' => ARRAY(0x183c654) = (1 2 3 4)
'key2' => ARRAY(0x182c1ac) = (5 6 7 8)

Trying to add element='9' for key='key2':
Hash contains elements:
'key1' => ARRAY(0x183c654) = (1 2 3 4)
'key2' => ARRAY(0x182bd9c) = (5 6 7 8 9) 

RE: Find if Hash Value exists in Hash of Arrays

CODE

#!/usr/bin/perl
use strict;
use warnings FATAL => qw/ all /;
use List::MoreUtils qw/ any /;
use Data::Dumper;

# construct hash
my %hash;
push @{$hash{key1}}, $_ for ( 1 .. 4 );
push @{$hash{key2}}, $_ for ( 5 .. 9 );

# process hash
my $var1 = 1;
while ( my ( $key, $list ) = ( each %hash ) )
{
    push @$list, $var1 unless ( any { $_ == $var1 } @$list );
}

# print hash
print Dumper \%hash; 

Chris

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