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MathGroup Archive 2004

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Re: Union - simple question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg49033] Re: [mg49009] Union - simple question
  • From: DrBob <drbob at bigfoot.com>
  • Date: Tue, 29 Jun 2004 04:50:11 -0400 (EDT)
  • References: <200406280813.EAA04305@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

This works:

ts = {{{1, 2, 3}, 5},
     {{3, 8, 7}, 6},
     {{7, 8, 9}, 5},
     {{1, 2, 3}, 7}};
Union[ts, SameTest ->(#1[[2]] == #2[[2]] & )]

{{{1, 2, 3}, 5}, {{1, 2, 3},
    7}, {{3, 8, 7}, 6}}

Bobby

On Mon, 28 Jun 2004 04:13:56 -0400 (EDT), Steve Gray <stevebg at adelphia.net> wrote:

> 	I don't understand why Union here doesn't work. (Sort is ok.)
> I want Union to eliminate list items where element [[1,2]] is
> duplicated. In this case, the first and third are duplicated because
> they both have '5' there.
>
>       ts = {{{1,2,3},5}, {{3,8,7},6}, {{7,8,9},5}, {{1,2,3},7}};
> Sort [ts, #1[[2]] < #2[[2]] &]
> Union[ts, Sametest -> (#1[[2]] == #2[[2]]&)]
>
> Any help will be appreciated.
>
>



-- 
DrBob at bigfoot.com
www.eclecticdreams.net


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