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in reply to Re^3: how to compare column 1 to column 2 and vice versa from multiple rows.
in thread how to compare column 1 to column 2 and vice versa from multiple rows.

Could you please tell me what each line is doing in this code. 
if ( $seen{ join ' ', sort @F }++ ) {
    $uniq{$F[0]}++;
    $uniq{$F[1]}++;
}
END {
    print for keys %uniq;
}

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code: Thanks to ccn

Also, before I execute this code I fill the  @F from the file input right?

my @F = <DATA>;

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