Compare arrays remove identical

cdherold has asked for the wisdom of the Perl Monks concerning the following question:

fellow monks,

I have two array's ... @kansas and @oklahoma. I want to compare the two arrays, determine identical content and then remove that content from @kansas.

The problem (for me) is how to find identical content.

Once I find the identical content I intend to remove it using splice() function.

Any ideas on how to get the identical content between the two arrays?

thanks

Comment on Compare arrays remove identical

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Re: Compare arrays remove identical by wardk (Deacon) on May 02, 2001 at 01:24 UTC
chapter 4.7 of the Perl cookbook node How can I find the union/difference/intersection of two arrays? may also be helpful	[reply]
Re: Compare arrays remove identical by perlmonkey (Hermit) on May 02, 2001 at 11:26 UTC
Theres a section in Mastering Algorithms with Perl on sets also. If you need a full implementation of unions/differences/intersections etc see the Set::Scalar module. If you use chromatic's code linked to above, I gave into my compulsion to do a tiny bit of benchmarking: `my @kansas = qw( corn wheat hay cattle ); my @oklahoma = qw( wheat dairy cattle ); use Benchmark; timethese(100000, { "diff1" => sub { diff1(\@kansas, \@oklahoma) }, "diff2" => sub { diff2(\@kansas, \@oklahoma) }, }); sub diff1 { my %hash; @hash{@{$_[1]}} = (1) x @{$_[1]}; return grep { !defined $hash{$_} } @{$_[0]}; } sub diff2 { my %hash = map{ $_=>1} @{$_[1]}; return grep { !defined $hash{$_} } @{$_[0]}; }` [download] It seems that a hash slice is a teeny bit faster than map for this purpose: Results: `Benchmark: timing 100000 iterations of diff1, diff2... diff1: 2 wallclock secs ( 1.74 usr + 0.01 sys = 1.75 CPU) diff2: 3 wallclock secs ( 2.22 usr + 0.01 sys = 2.23 CPU)` [download]	[reply] [d/l] [select]