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MathGroup Archive 2004

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RE: Re: how to delete duplicate items in the same list

  • To: mathgroup at smc.vnet.net
  • Subject: [mg45585] RE: [mg45576] Re: how to delete duplicate items in the same list
  • From: "David Park" <djmp at earthlink.net>
  • Date: Fri, 16 Jan 2004 06:05:00 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Union is a set operation. As far as I know, sets do not have duplicate
elements. The basic operation of Union is to combine the elements from
several sets. It eliminates duplicates as a side effect. (The same element
might appear on two or more subsets.)

So when we use Union on just one set of elements we are just using the side
effect to eliminate duplicates.

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/

From: AES/newspost [mailto:siegman at stanford.edu]
To: mathgroup at smc.vnet.net

> > I can't find a way to make sure all items in the same list are unique.
Can
> > anybody help me out? Thanks a lot!

> Union[a]==a


Can anyone explain why "Union" means what it does?  -- or at least a
mental crutch to help me remember that Union is the command that does
this?

(Doesn't seem an obvious name for the function involved, though I
suppose I could try to think "Unique" --->  "Union")



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