Re: Match Pairs of Numbers
- To: mathgroup at smc.vnet.net
- Subject: [mg86936] Re: Match Pairs of Numbers
- From: Szabolcs Horvát <szhorvat at gmail.com>
- Date: Wed, 26 Mar 2008 04:56:48 -0500 (EST)
- Organization: University of Bergen
- References: <fsa5bn$aae$1@smc.vnet.net>
Andrew Beveridge wrote:
> Any help would be appreciated.
>
> I am using Mathematica 5.2 & 6.0
>
> I am having trouble finding the correct form of Pattern Matching for
> pairs of Numbers. I do not know whether to use Select, Cases, Pick,
> etc. I am also unsure how to set the pattern matching argument.
>
> Assume I have the list
>
> lst = {{1,1}, {1,2}, {1,3}, {1,4}, {2,2}, {3,1}, {3,2}, {3,3}, {4,1}, {4,4}}
>
>
> I would like to match/select pairs that have the same set of numbers
> only reversed, that is, the selection would find
>
> {{1,3}, {3,1}, {1,4}, {4,1} }
>
Intersection[lst, Reverse /@ lst]
Select[%, UnsameQ @@ # &]