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Re: Keeping order with Union

  • To: mathgroup at smc.vnet.net
  • Subject: [mg32603] Re: Keeping order with Union
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Thu, 31 Jan 2002 01:45:28 -0500 (EST)
  • Organization: Universitaet Leipzig
  • References: <a38bd0$2n$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

look in the "Future Examples" of the Mathematica Online Help for Union[]
!

UnsortedUnion[x_] := Module[{f}, f[y_] := (f[y] = Sequence[]; y); f /@
x]

Regards
  Jens

Dave Snead wrote:
> 
> I'd like a function that throws out duplicate entries in a list and keeps
> the
> original list order.  (when it sees 2 equal entries it throws out the one
> that is later in the list).   I'd use Union, but it sometimes changes the
> order of the elements in the list.  What's the tersest way to do this?
> Thanks in advance,
> Dave Snead


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