CODEWITHSUNDEEP
arraysperlhashhashmapcompare
Jill448
Jill448

Reputation: 1793

Perl Compare hash of arrays with another array

I am trying to compare all the array values (complete array) with a hash's value(which is array) and if the match founds,then push the key of hash to new array. The below code compare if the hash value is not array but how can I compare if its array?

%hash=(
       storeA=>['milk','eggs'],
       storeB=>['milk','fruits','eggs','vegetables'],
       storeC=>['milk','fruits','eggs'],
      );

@array = (
        'fruits',
        'milk',
        'eggs'
    );

Code to compare

use strict;
use warnings;
use Data::Dumper;

foreach my $thing (@array)   {
     foreach ((my $key, my $value) = each %hash)   { 
                 if ($value eq $thing)   {
                       push @new_array, $key;
                }
          }
   }
  print Dumper(\@new_array);

Expected Output

@new_array = (
               storeB,
               storeC
       );

Upvotes: 0

Views: 975

Answers (5)

zdim
zdim

Reputation: 66883

Go through all stores (keys) and for each check whether all array elems are in the key's array-ref.

use strict;
use warnings;

my %inventory = (
    storeA => ['milk','eggs'],
    storeB => ['milk','fruits','eggs','vegetables'],
    storeC => ['milk','fruits','eggs'],
);    
my @items = ('fruits', 'milk', 'eggs');

my @found;
foreach my $store (keys %inventory) {
    push @found, $store 
        if @items == grep { in_store($_, $inventory{$store}) } @items
}   

sub in_store { for (@{$_[1]}) { return 1 if $_[0] eq $_ }; return 0; }

print "@found\n";  # prints:  storeB storeC

The grep block checks for each item whether it is (available) in the store, and if the number of those that pass is equal to the number of items (array size) that store has all items and is added. Note that a subroutine returns the last value evaluated without an explicit return, so the final return is not needed. It was added for clarity.

Upvotes: 0

Borodin
Borodin

Reputation: 126722

I would build a hash out of each store's stock array. It's a wasteful method, but not egregiously so as long as the real data isn't enormous

Like this. The inner grep statement counts the number of items in @list that are available at this store and compares it to the number of items in the list, returning true if everything is in stock

If this is a real situation (I suspect it's homework) then for all practical purposes that I can think of, the %stocks hash should contain hashes of the items available at each store

use strict;
use warnings 'all';

my %stocks = (
    storeA => [ qw/ milk eggs / ],
    storeB => [ qw/ milk fruits eggs vegetables / ],
    storeC => [ qw/ milk fruits eggs / ],
);

my @list = qw/ fruits milk eggs /;

my @stores = grep {
    my %stock = map { $_ => 1 } @{ $stocks{$_} };
    grep($stock{$_}, @list) == @list;
} keys %stocks;

use Data::Dump;
dd \@stores;

output

["storeB", "storeC"]

Upvotes: 1

mkHun
mkHun

Reputation: 5927

Simply try this. One small trick i done here. grep was use to filter the element from an array.

I created the variable $joined_array which contain the | separated @array data. Then i pass the variable into the grep.

And the trick is, when the array is compare with a scalar data, the comparison is behave, the total number of an array element with scalar data. 

my @array = qw(one two three);

if(@array == 3)
{
    print "Hi\n";

}

Here condition is internally run as 3 == 3.

That the same logic i done here. 

use warnings;
use strict;
my %hash=(
    "storeA"=>['milk','eggs'],
    "storeB"=>['milk','fruits','eggs','vegetables'],
    "storeC"=>['milk','fruits','eggs'],
);

my @array = (
    'fruits',
    'milk',
    'eggs'
);

my @new_array;

my $joined_array = join("|",@array);

foreach (keys  %hash)
{

 push(@new_array,$_) if  ((grep{ /\b$joined_array\b/ } @{$hash{$_}}) >= scalar @array);

}

print "$_\n" for @new_array

Upvotes: 1

Håkon Hægland
Håkon Hægland

Reputation: 40758

You could also use a combination of all and any form List::Util :

while ((my $key, my $value) = each %hash) {
    if ( all { my $temp = $_; any { $_ eq $temp } @$value } @array ) {  
        push @new_array, $key;
    }
}

So here you are looking for the case where all the elements of @array exists in the given array from the hash.

Upvotes: 2

choroba
choroba

Reputation: 241878

Find the intersection of the two sets, if the number of its elements is the number of the elements in the array, you want to store the key:

#!/usr/bin/perl
use warnings;
use strict;


sub intersect {
    my ($arr1, $arr2) = @_;
    my %intersection;
    $intersection{$_}{0}++ for @$arr1;
    $intersection{$_}{1}++ for @$arr2;
    return grep 2 == keys %{ $intersection{$_} }, keys %intersection
}


my %hash = (
            storeA => [qw[ milk eggs ]],
            storeB => [qw[ milk fruits eggs vegetables ]],
            storeC => [qw[ milk fruits eggs ]],
           );

my @array = qw( fruits milk eggs );

my @new_array;

while (my ($store, $arr) = each %hash) {  # while, not for!
    push @new_array, $store if @array == intersect(\@array, $arr);
}

use Data::Dumper;
print Dumper(\@new_array);

Upvotes: 1

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