finding duplicates in an array

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

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Re: finding duplicates in an array by Roy Johnson (Monsignor) on Jan 26, 2006 at 16:00 UTC
You probably want to use grep along with a hash for removing duplicates from an array. Caution: Contents may have been coded under pressure.	[reply]
Re^2: finding duplicates in an array--> WRONG QUESTION by Anonymous Monk on Jan 27, 2006 at 10:00 UTC
Hi, thanx to both of you! I have made a mistake in my question.. what i have is an array of arrays that i want to make unique. That is, I have: @AoA=(["1","15"], ["2","5"], ["3","4"], ["3","5"], ["3","8"], ["3","5"], ["4","6"], ["4","5"]) and I want to remove array element ["3","5"] which is seen twice if you notice. Is that possible?	[reply]
Re^3: finding duplicates in an array--> WRONG QUESTION by davorg (Chancellor) on Jan 27, 2006 at 10:57 UTC
You just need to be a bit cleverer about the keys in your `%seen` hash. `#!/usr/bin/perl use strict; use warnings; use Data::Dumper; my @AoA=(["1","15"], ["2","5"], ["3","4"], ["3","5"], ["3","8"], ["3","5"], ["4","6"], ["4","5"]); my %seen; @AoA = grep { ! $seen{join $;, @$_}++ } @AoA; print Dumper \@AoA;` [download] -- <http://dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply] [d/l]
Re: finding duplicates in an array by EvanK (Chaplain) on Jan 26, 2006 at 15:54 UTC
to clarify, I assume you're using a multi-dimensional array, where each element contains another two-element array? `$array[0] = [1,12]; $array[1] = [1,13]; $array[2] = [2,14]; #etc...` [download] or are these literal strings? `$array[0] = "(1,12)"; $array[0] = "(1,13)"; $array[0] = "(2,14)"; #etc...` [download] __________ Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life. - Terry Pratchett	[reply] [d/l] [select]
Re: finding duplicates in an array by planetscape (Chancellor) on Jan 27, 2006 at 14:17 UTC
You may also wish to take a look at these nodes: How to find and remove duplicate elements from an array? How can I display a unique array if it contains some repeated elements HTH, planetscape	[reply]
Re: finding duplicates in an array by Anonymous Monk on Feb 04, 2008 at 23:24 UTC
Hey. I have a question really similar to this one: Let's say I have an array with: `(1, 1) (1, 2) (1, 3) (1, 4) (1, 5) (2, 3) (2, 3) (4, 1) (5, 1)` [download] If I wanted to get rid of duplicates of (x, y) AND get rid of any duplicates of the reverse (y, x), how would I best do this? ie, I want to end up with: `(1, 1) (1, 2) (1, 3) (1, 4) or (4, 1) (1, 5) or (5, 1) (2, 3)` [download] Really appreciate any suggestions! Thanks!	[reply] [d/l] [select]
Re^2: finding duplicates in an array by bobf (Monsignor) on Feb 05, 2008 at 03:10 UTC
If the order of the elements in each (x, y) pair really doesn't matter, then sorting them should result in data that can then be processed using the techniques in finding duplicates in an array. In other words, make both `(1, 4)` and `(4, 1)` into the same pair. Was that enough of a hint, or do you need an example? Update: I couldn't resist. `my @aoa = ( [1,4], [4,1] ); my @sorted = map { [ sort { $a <=> $b } @$_ ] } @aoa;` [download]	[reply] [d/l] [select]