How to make an array from an array?

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

Hi. I have array @all_names=(john, andy, bill,andy, john, julia, bill). What I'd like to do is make an other array based on the first array. Array called @names should have every name just one time: (john,andy,bill, julia)
Pasi

Comment on How to make an array from an array?

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Re: How to make an array from an array? by barrd (Canon) on Dec 06, 2003 at 14:47 UTC
Straight from Perl Cookbook (well almost :-) `my @all_names = qw/john andy bill andy john julia bill/; my %seen = (); my @names = grep { ! $seen{$_} ++ } @all_names; print join(' ', @names);` [download] This prints `john andy bill julia`, I'm sure you'll get other variations. Update 1: Fixed typos in code D'oh. Update 2: As TomDLux rightly pointed out, you may wish to `sort` the names alphabetically, if so just change line 3 to this: `my @names = sort grep { ! $seen{$_} ++ } @all_names;` [download] Returning: `andy bill john julia` (which is what I meant to do originally but ... err... didn't)	[reply] [d/l] [select]
Re: How to make an array from an array? by TomDLux (Vicar) on Dec 06, 2003 at 14:50 UTC
This is a frequently asked question, the Search window will find the answer for you. If order doesn't matter, use the values as keys to a hash, then extract a list of the keys. If order does matter, go through the list, copying elements which have not been seen yet. As each element is copied, mark it as seen by setting a hash element. go through the original array, checking whether an element has been seen yet, `unsplice`-ing duplicates. Good luck with your homework. -- `TTTATCGGTCGTTATATAGATGTTTGCA`	[reply]
Re: How to make an array from an array? by Anonymous Monk on Dec 06, 2003 at 15:15 UTC
So you're looking to eliminate duplicates? perldoc -q duplicate Found in C:\Perl\lib\pod\perlfaq4.pod How can I remove duplicate elements from a list or array? :)	[reply]
Re: How to make an array from an array? by etcshadow (Priest) on Dec 07, 2003 at 05:02 UTC
`@unique_list = keys %{{map{($_=>1)} @non_unique_list}};` ------------ :Wq Not an editor command: Wq	[reply] [d/l]
Re: How to make an array from an array? by Anonymous Monk on Dec 07, 2003 at 08:02 UTC
Thank you all for bothering to answer. You have solved my problem. As you might have noticed :) english is not my native lanquage. So it's sometimes difficult to make searches because of not knowing the right expressions or words for something. Pasi	[reply]

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