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Find if Hash Value exists in Hash of Arrays

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stevio

stevio

Vendor
Jul 24, 2002
78
AU
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";
}

 
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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
 
Upvote 0 Downvote
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";
	}
  }
}

 
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For example:
stevio.pl
Code: 
[COLOR=#804040][b]use strict[/b][/color];
[COLOR=#0000ff]#use warnings;[/color]

[COLOR=#804040][b]my[/b][/color] [COLOR=#008080]$key[/color] = [COLOR=#ff00ff]""[/color];
[COLOR=#804040][b]my[/b][/color] [COLOR=#008080]%lst_hash[/color] = ();

[COLOR=#0000ff]# populate hash[/color]
[COLOR=#0000ff]# key1[/color]
[COLOR=#008080]$key[/color] = [COLOR=#ff00ff]'[/color][COLOR=#ff00ff]key1[/color][COLOR=#ff00ff]'[/color];
[COLOR=#804040][b]my[/b][/color] [COLOR=#008080]@lst[/color] = ([COLOR=#ff00ff]1[/color] .. [COLOR=#ff00ff]4[/color]);
[COLOR=#0000ff]# add reference of @lst[/color]
[COLOR=#008080]$lst_hash{$key}[/color] =  \[COLOR=#008080]@lst[/color];

[COLOR=#008080]$key[/color] = [COLOR=#ff00ff]'[/color][COLOR=#ff00ff]key2[/color][COLOR=#ff00ff]'[/color];
[COLOR=#804040][b]my[/b][/color] [COLOR=#008080]@lst[/color] = ([COLOR=#ff00ff]5[/color] .. [COLOR=#ff00ff]8[/color]);
[COLOR=#0000ff]# add reference of @lst[/color]
[COLOR=#008080]$lst_hash{$key}[/color] =  \[COLOR=#008080]@lst[/color];

[COLOR=#0000ff]# print hash[/color]
[COLOR=#804040][b]print[/b][/color] [COLOR=#ff00ff]"[/color][COLOR=#ff00ff]Hash contains elements:[/color][COLOR=#6a5acd]\n[/color][COLOR=#ff00ff]"[/color];
print_hash();

[COLOR=#008080]$key[/color] = [COLOR=#ff00ff]'[/color][COLOR=#ff00ff]key1[/color][COLOR=#ff00ff]'[/color];
[COLOR=#804040][b]my[/b][/color] [COLOR=#008080]$element[/color] = [COLOR=#ff00ff]3[/color];
[COLOR=#804040][b]print[/b][/color] [COLOR=#ff00ff]"[/color][COLOR=#ff00ff]Trying to add element='[/color][COLOR=#008080]$element[/color][COLOR=#ff00ff]' for key='[/color][COLOR=#008080]$key[/color][COLOR=#ff00ff]':[/color][COLOR=#6a5acd]\n[/color][COLOR=#ff00ff]"[/color];
value2hash([COLOR=#008080]$key[/color], [COLOR=#008080]$element[/color]);
[COLOR=#804040][b]print[/b][/color] [COLOR=#ff00ff]"[/color][COLOR=#ff00ff]Hash contains elements:[/color][COLOR=#6a5acd]\n[/color][COLOR=#ff00ff]"[/color];
print_hash();

[COLOR=#008080]$key[/color] = [COLOR=#ff00ff]'[/color][COLOR=#ff00ff]key2[/color][COLOR=#ff00ff]'[/color];
[COLOR=#008080]$element[/color] = [COLOR=#ff00ff]9[/color];
[COLOR=#804040][b]print[/b][/color] [COLOR=#ff00ff]"[/color][COLOR=#ff00ff]Trying to add element='[/color][COLOR=#008080]$element[/color][COLOR=#ff00ff]' for key='[/color][COLOR=#008080]$key[/color][COLOR=#ff00ff]':[/color][COLOR=#6a5acd]\n[/color][COLOR=#ff00ff]"[/color];
value2hash([COLOR=#008080]$key[/color], [COLOR=#008080]$element[/color]);
[COLOR=#804040][b]print[/b][/color] [COLOR=#ff00ff]"[/color][COLOR=#ff00ff]Hash contains elements:[/color][COLOR=#6a5acd]\n[/color][COLOR=#ff00ff]"[/color];
print_hash();


[COLOR=#804040][b]sub [/b][/color][COLOR=#008080]print_hash [/color]{
  [COLOR=#0000ff]# print hash[/color]
  [COLOR=#804040][b]foreach[/b][/color] [COLOR=#008080]$key[/color] ([COLOR=#804040][b]sort[/b][/color] [COLOR=#804040][b]keys[/b][/color]([COLOR=#008080]%lst_hash[/color])){
    [COLOR=#0000ff]# dereference list[/color]
    [COLOR=#804040][b]my[/b][/color] [COLOR=#008080]@tmp_lst[/color] = [COLOR=#008080]@{$lst_hash{$key}}[/color];
    [COLOR=#804040][b]print[/b][/color] [COLOR=#ff00ff]"[/color][COLOR=#ff00ff]'[/color][COLOR=#008080]$key[/color][COLOR=#ff00ff]' => [/color][COLOR=#008080]$lst_hash{$key}[/color][COLOR=#ff00ff] = ([/color][COLOR=#008080]@tmp_lst[/color][COLOR=#ff00ff])[/color][COLOR=#6a5acd]\n[/color][COLOR=#ff00ff]"[/color];
  }
  [COLOR=#804040][b]print[/b][/color] [COLOR=#ff00ff]"[/color][COLOR=#6a5acd]\n[/color][COLOR=#ff00ff]"[/color];
}

[COLOR=#804040][b]sub [/b][/color][COLOR=#008080]value2hash [/color]{
  [COLOR=#0000ff]# add value to hash if it doesn't exist[/color]
  [COLOR=#804040][b]my[/b][/color] ([COLOR=#008080]$key[/color], [COLOR=#008080]$val[/color]) = [COLOR=#008080]@_[/color];
  [COLOR=#0000ff]# dereference list[/color]
  [COLOR=#804040][b]my[/b][/color] [COLOR=#008080]@lst[/color] = [COLOR=#008080]@{$lst_hash{$key}}[/color];
  [COLOR=#804040][b]my[/b][/color] [COLOR=#008080]$val_exist[/color] = [COLOR=#ff00ff]0[/color];
  [COLOR=#804040][b]foreach[/b][/color] [COLOR=#804040][b]my[/b][/color] [COLOR=#008080]$j[/color] ([COLOR=#008080]@lst[/color]) {
     [COLOR=#804040][b]if[/b][/color] ([COLOR=#008080]$j[/color] == [COLOR=#008080]$val[/color]) { 
      [COLOR=#008080]$val_exist[/color] = [COLOR=#ff00ff]1[/color];
      [COLOR=#804040][b]last[/b][/color];
    }
  }

  [COLOR=#804040][b]if[/b][/color] ([COLOR=#008080]$val_exist[/color] == [COLOR=#ff00ff]0[/color]) {
     [COLOR=#804040][b]push[/b][/color] ([COLOR=#008080]@lst[/color], [COLOR=#008080]$val[/color]) 
  }
  [COLOR=#804040][b]else[/b][/color] {
    [COLOR=#804040][b]print[/b][/color] [COLOR=#ff00ff]"[/color][COLOR=#ff00ff]ERROR: For key = '[/color][COLOR=#008080]$key[/color][COLOR=#ff00ff]' value [/color][COLOR=#008080]$val[/color][COLOR=#ff00ff] already exists ![/color][COLOR=#6a5acd]\n[/color][COLOR=#ff00ff]"[/color];
  }
  [COLOR=#0000ff]# add reference of @lst[/color]
  [COLOR=#008080]$lst_hash{$key}[/color] =  \[COLOR=#008080]@lst[/color];
}

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)

 
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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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