Greetings to you, oh great Monks

I would like to compare two arrays and keep only those elements that PARTIALLY intersect. For example, let the two array's be:

@arr1 = ("0000007 | John | ABC.txt | 42","0000014 | Jane | XYZ.txt | 34","0000017 | Jessica | GHI.txt | 21", etc);
@arr2 = (0000007, 0000014);
This should result in a text file arr3.dat that contains something like
0000007 | John | ABC.txt | 42
0000014 | Jane | XYZ.txt | 34

I know I should use hashes and know how to split element-by-element but can't figure this one out.

EDIT: CODE ADDED, SORRY FOR BEING UNSPECIFIC. THE FINAL ROW SUGGESTS THAT THE HASHING GOES WRONG...
EDIT AGAIN: SOLUTION BY nemesdani WORKS FINE (BUT SEE MY REPLY).
Thanks! 


use feature ':5.10';

open (KEYFILE, "arr2.txt");
    @arr2 = <KEYFILE>;
close(KEYFILE);

# Declare and fill up the hash
my %elements;
foreach (@arr2) {
    $elements{$_} = 1;
};

#I'm repeating this for several quarterly files:
for($year=2006; $year<2012; $year=$year+1){
    for($i=1; $i<5; $i=$i+1){
    
        # Load each quarterly file
        $filea = $year . "QTR" . $i . "arr1.txt";
        open(MYINFILE, $filea);
            @arr1 = <MYINFILE>;
        close(MYINFILE);
        $sizegn = @arr1;

        # For each entry in the quarterly file
        for($j=0; $j<$sizegn; $j++){
            
            # Pick only lines that contain the string "txt"
            if($arr1[$j] =~ m/txt/){
            
                # splits the elements of @arr1, and format the first e
+lement into 7-digit number:
                @arraydata = split(/\|/, $arr1[$j]); 
                my $element = sprintf("%07d", $arraydata[0]); 
                
                # now check if $element is in hash :
                if (exists $elements{$element}){
                    open(MYOUTFILE, ">>Arr3.dat");
                    print MYOUTFILE $arr1[$j];
                    close(MYOUTFILE);
                }
                print "D'oh - '$element' not found\n" unless (exists $
+elements{$element});
            }
        }
    }
}

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In reply to Deleting elements of one list using another by Sj03rd

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