in reply to Re: Re: comparing two arrays
in thread comparing two arrays

No one has mentioned the Cookbook yet, so i will.

If you need @file to contain at least all the elements of @report, then you need to find the simple difference of the two. The simple difference is the (paraphrasing from the Cookbook) "set of members of @report, but not of @file". If this set is empty, then @file contains at least all the elements of @report. So, working with Recipe 4.7:

use strict; my @report = qw(sqltable mike_test sarak_mike); my @file = (@report, qw(plus a little more)); # off by 0 print '@file was off by ' . simple_compare(\@report,\@file) . " elements\n"; # still 0, that elem wasn't in @report pop @file; print '@file was off by ' . simple_compare(\@report,\@file) . " elements\n"; # off by 1, that one was shift @file; print '@file was off by ' . simple_compare(\@report,\@file) . " elements\n"; # returns number of elements in A that aren't in B sub simple_compare { my ($A,$B) = @_; # build lookup table my %seen = map { $_ => 1 } @$B; # find those in A that aren't in B my @aonly; foreach my $item (@$A) { push @aonly,$item unless ($seen{$item}); } return scalar @aonly; }
(Array::Compare has a simple_compare() method, but it's definition of a simple compare is not the same as the Cookbook's.)

Also note that this could only a be partial solution. What if you needed to compare these two arrays:

my @report = qw(one one two); my @file = qw(one two two);
Now what? @file definitely contains at least one of each element from @report. But, @file doesn't contain 2 'one's like @report does. If you need something like this, but you don't care about order, then use rob_au's suggestion and sort the arrays first. If you do care about order, use that code verbatim. Hope this helps!

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
F--F--F--F--F--F--F--F--
(the triplet paradiddle)

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Re: (jeffa) 2Re: comparing two arrays
by jdelmedi (Initiate) on Nov 24, 2001 at 23:46 UTC
    Thanks for your help. I'm so close, but something is not working. I am trying to debug the following, but it seems that although both the @file contain the @report strings, I am not getting a match. Is it possible when I load the text file into @file array, that the elements are not compared as strings? Frusterating!!!!! The contents of the @file looks like this:
    sqltable_mike table loaded successfully with 282873
    sarak_mike table loaded successfully with 282873 records
    sticks table loaded successfully with 282873 records.
    hello table loaded successfully with 282873 records.
    All I need it to do is match all @report contents with the internal @file. What am I doing wrong. Your assistance is greatly appreciated. <CODE> use strict;
    my @compare=();
    my $file='d:\mms_tableload.txt';
    my @file="";
    open(FILE,"<$file");
    @file = <FILE>;
    close(FILE);
    my @report = qw(sqltable_mike sarak_mike );
    my @compare = ( @report, qw (@file ));
    # off by 0
    print '@file was off by '
    . simple_compare(\@report,\@compare)
    . " elements\n";
    # still 0, that elem wasn't in @report
    pop @file;
    print '@file was off by '
    . simple_compare(\@report,\@compare)
    . " elements\n";
    # off by 1, that one was
    shift @file;
    print '@file was off by '
    . simple_compare(\@report,\@file)
    . " elements\n";
    # returns number of elements in A that aren't in B
    sub simple_compare {
    my ($A,$B) = @_;
    # build lookup table
    my %seen = map { $_ => 1 } @$B;
    # find those in A that aren't in B
    my @aonly;
    foreach my $item (@$A) {
    push @aonly,$item unless ($seen{$item});
    }
    return scalar @aonly;
    }
    <CODE>
      This is a problem:
      @file = ; # you probably meant @file = <FILE>; # and then you need to chomp @file; # to remove trailing new lines

      jeffa