From: John W Higgins <wishdev@...>
Date: 2009-09-26T00:55:09+09:00
Subject: Re: How to remove duplicate elements in a 2D array

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Sorry about the last response - hit the wrong button.....

On Fri, Sep 25, 2009 at 8:34 AM, Li Chen <chen_li3@yahoo.com> wrote:

> Hi all,
>
> I have a 2D array as follow:
>
> arr=[
>
>     [ 'a',1,2,3],
>     ['b',4,5,6],
>     ['c',3,2,1],
>     ['a',1.3,2.2,3,3],
>     ...
>     ['a', 2,1,3],
>   ...
>   ['a',2.1,1.5,3]
>
> ]
>
> As you can see there are several rows containing  element 'a',
> and the last row containing 'a'' is the lastest one.  I wonder if it
> is possible to return a new array which contains the latest row having
> 'a' ,
> together with other rows.
>
>
Lets try this again shall we....

seen = [] # this stores the first elements as we pass through them
#we reverse the array because you want the last elements to be the ones
returned
#select will add an element to the return value if the block is true
arr.reverse.select{ |x|
  check = !(seen.include?(x[0])) #we check to see if we've seen this first
element before
  seen << x[0] #add the first element to our "seen" list - we don't care if
it's in here multiple times
  check #the block equals the check value
}.reverse #since we reversed once we want to do so again to get the correct
order back

John


>
> Thanks,
>
> Li
> --
> Posted via http://www.ruby-forum.com/.
>
>

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