Best way to compare 4 arrays

Question

I have 4 files, each file I read into it's own array. From there i then compare files A, B and C to each other. At each step I print out a list of numbers which are missing.

Compare A to B then B to A Print list of files found in A and not B and vise versa

Compare A to C then C to A Print list of files found in A but not C and vise versa

Compare B to C and C to B Print list of files found in B but not C and vise versa

Then I must take the values from these comparisons and compare them to file D print only the files that are not found in file D

Here is the code I have so far. I just think that there could be a better way of doing this and I would like some assistance with this.

[CODE]

sub compare {

    my ($nf, $of, $inf, $infw) = @_;

    open NF, $nf or die $!;
    my @note_file = <NF>;
    close NF;

    open OF, $of  or die $!;
    my @order_file = <OF>;
    close OF;

    open INF, $inf or die $!;
    my @invoice_file = <INF>;
    close INF;

    open INFW, $infw or die $!;
    my @invoicefw_file = <INFW>;
    close INFW;

    my $lc1 = List::Compare->new(\@note_file,\@order_file); 
    my @unique_in_note_file = $lc1->get_unique;
    my @unique_in_order_file = $lc1->get_complement;
    print "The following files exist only in the Brighton-Note file and not in the Brighton-Order file : " . "\n\n" . join("\n", @unique_in_note_file) . "\n" if(scalar(@unique_in_note_file) > 0);
    print "The following files exist only in the Brighton-Order file and not in the Brighton-Note file : " . "\n\n" . join("\n", @unique_in_order_file) . "\n" if(scalar(@unique_in_order_file) > 0);

    my $lc2 = List::Compare->new(\@note_file,\@invoice_file);
    @unique_in_note_file = $lc2->get_unique;
    my @unique_in_invoice_file = $lc2->get_complement;
    print "The following files exist only in the Brighton-Note file and not in the Web-Sales file : " . "\n\n" . join("\n", @unique_in_note_file) . "\n" if(scalar(@unique_in_note_file) > 0);
    print "The following files exist only in the Web-Sales file  and not in th Brighton-Note file : " . "\n\n" . join("\n", @unique_in_invoice_file) . "\n" if(scalar(@unique_in_invoice_file) > 0);

    my $lc3 = List::Compare->new(\@order_file, \@invoice_file);
    @unique_in_order_file = $lc3->get_unique;
    @unique_in_invoice_file = $lc3->get_complement;
    print "The following files exist only in the Brighton-Order file and not in the Web-Sales file : " . "\n\n" . join("\n", @unique_in_order_file) . "\n" if(scalar(@unique_in_order_file) > 0);
    print "The following files exist only in the Web-Sales file  and not in th Brighton-Order file : " . "\n\n" . join("\n", @unique_in_invoice_file) . "\n" if(scalar(@unique_in_invoice_file) > 0);

    my $lc4 = List::Compare->new(\@unique_in_note_file,\@invoicefw_file);
    my @unique_in_notefw_file = $lc4->get_unique;
    my @unique_in_invoicefw_file = $lc4->get_complement;
    print "The following files exist only in the Brighton-Note file and not in the Web-SalesFW file : " . "\n\n" . join("\n", @unique_in_notefw_file) . "\n" if(scalar(@unique_in_notefw_file) > 0);
    print "The following files exist only in the Web-SalesFW file  and not in th Brighton-Note file : " . "\n\n" . join("\n", @unique_in_invoicefw_file) . "\n" if(scalar(@unique_in_invoicefw_file) > 0);

    my $lc5 = List::Compare->new(\@unique_in_order_file,\@invoicefw_file);
    my @unique_in_orderfw_file = $lc5->get_unique;
    @unique_in_invoicefw_file = $lc5->get_complement;
    print "The following files exist only in the Brighton-Order file and not in the Web-SalesFW file : " . "\n\n" . join("\n", @unique_in_orderfw_file) . "\n" if(scalar(@unique_in_orderfw_file) > 0);
    print "The following files exist only in the Web-SalesFW file  and not in th Brighton-Order file : " . "\n\n" . join("\n", @unique_in_invoicefw_file) . "\n" if(scalar(@unique_in_invoicefw_file) > 0);

}

jordanm - I have not let me look at the man pages on that. Thank you for the tip. — Leo.Cruz, Apr 04 '13 at 13:52

score 4 · Accepted Answer · answered Apr 02 '13 at 05:51

4

The typical way of doing this with two files is:

my %items;
while (<$file1>) {
  $items{$_}++;
}
while (<$file2>) {
  $items{$_}++;
}

Any key in %items which has a value of 2 is in both files; any key with a value of 1 is only in one file.

If you need to know which file(s) each value appears in, this can be generalized by adding different numbers for each file. e.g., If you add 100 for lines in the first file, 10 for lines in the second file, and 1 for lines in the third file, then you can immediately see that a key with the value 101 represents a line that is in the first and third files, but not in the second.

answered Apr 02 '13 at 05:51

Dave Sherohman

45,363
14
64
102

1

What Dave is describing with adding 100/10/1 depending on the file is a form of using bitfields. A good article on perl and bit fields is here: http://www.effectiveperlprogramming.com/blog/714 – RickF Apr 02 '13 at 22:03
Thanks for the link, RickF! A real bitfield is definitely more efficient and it's what I would probably use in The Real World. The primary reason I opted for powers of 10 in the example is because they're easier to see visually. – Dave Sherohman Apr 03 '13 at 06:38
1

The only problem with doing it by adding powers of ten shows up if you have redundant entries in the list. – RickF Apr 03 '13 at 16:43
Dave - thank you for your suggestion. I can see it working in my case because I strip out any redundant values from all files. @RickF thank you very much for the link I was not aware of bitfields I am definitely going to read the article. – Leo.Cruz Apr 04 '13 at 13:55

Best way to compare 4 arrays

1 Answers1