From: Robert Klemme <shortcutter@...>
Date: 2007-05-11T16:10:05+09:00
Subject: Re: how to remove dups from 2 lists?

On 11.05.2007 06:46, Alex Gutteridge wrote:
> On 11 May 2007, at 11:18, Mike Steiner wrote:
> 
>> def RemoveDupsFromLists ( list1 , list2 )
>>    list1.each_index do | i |
>>        list2.each_index do | j |
>>            if list1[i] == list2[j]
>>                list1.delete_at ( i )
>>                list2.delete_at ( j )
>>            end
>>        end
>>    end
>>    return [ list1 , list2 ]
>> end
> 
> Here is how I would write it: (it didn't give quite the same results as 
> your method but seems to be closer to what you asked for so...):
> 
> def remove_duplicates(list1,list2)
>   (list1 & list2).each do |x|
>     list1.delete(x)
>     list2.delete(x)
>   end
>   return list1,list2
> end
> 
> irb(main):028:0> RemoveDupsFromLists([1,1,2,3,4],[2,2,3,5,5])
> => [[1, 1, 4], [2, 5, 5]]
> irb(main):029:0> remove_duplicates([1,1,2,3,4],[2,2,3,5,5])
> => [[1, 1, 4], [5, 5]]
> 
> Be careful with your method since it alters the Arrays as you iterate 
> through them and will give hard to understand results sometimes. In the 
> example above '2' is a duplicate but is only deleted from the second 
> array once because of this problem/feature.

Sets also come in handy - especially if those lists are large.

Kind regards

	robert