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Re: Finding shared element in two lists

  • To: mathgroup at smc.vnet.net
  • Subject: [mg114089] Re: Finding shared element in two lists
  • From: Peter Breitfeld <phbrf at t-online.de>
  • Date: Tue, 23 Nov 2010 05:59:36 -0500 (EST)
  • References: <icdoc5$6ho$1@smc.vnet.net>

Jason Ebaugh wrote:

> I am trying to write a function that would take two lists of increasing more
> precise location, and return the most specific level of geography that they
> share.
>
> myhouse={"Earth", "North America", "USA", "Illinois", "Champaign County",
> "Urbana"};
> friendshouse={"Earth", "North America", "USA", "Minnesota", "Ramsey County",
> "St. Paul"};
>
> In this case, the function should output USA.
>
> I could do this procedurally well enough. But I am really trying to get
> comfortable with functional programming.
>
>
>
> The above is just a more digestible version of what I am really trying to
> do. I want to find the lowest level of taxonomy that two species share.
>
> Ex:
> aphid={"Insecta", "Dicondylia", "Pterygota", "Neoptera", "Paraneoptera",
> "Hemiptera", "Sternorrhyncha", "Aphidiformes", "Aphidomorpha", "Aphidoidea",
> "Aphididae", "Aphidinae", "Macrosiphini", "Acyrthosiphon"};
> mosquito={"Insecta", "Dicondylia", "Pterygota", "Neoptera", "Endopterygota",
> "Diptera", "Nematocera", "Culicimorpha", "Culicoidea"};
>
> answer = Neoptera
>
>
> Thank a 10^6,
> Jason


I'm not sure if this is the most elegant way, but it works for both of
your examples.

findMostPrecise[ll:{_List..}]:=
Module[{common},
  common=Intersection[Sequence@@ll];
  Last@Select[ll[[1]],MemberQ[common,#]&]
]

findMostPrecise[{mayhouse,friendhouse}]

Out= USA

findMostPrecise[{aphid,mosquito}]
Out= Neoptera

-- 
_________________________________________________________________
Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de


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