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Re: Finding position of an element in a list:

  • To: mathgroup at smc.vnet.net
  • Subject: [mg84039] Re: Finding position of an element in a list:
  • From: Bill Rowe <readnewsciv at sbcglobal.net>
  • Date: Fri, 7 Dec 2007 03:09:35 -0500 (EST)

On 12/6/07 at 2:43 AM, gopinathv at ou.edu (Gopinath Venkatesan) wrote:

>(This is an easy problem, but I was unable to get it work in
>Mathematica, probably because of the precision - I tried setting
>precision too, still got stuck)
>
>Suppose we have a list, xlis, having some elements, and I have to
>find one nearest value I am interested in that list. In the below
>example, I wanted to find the position of a number belonging to list
>and close to 6 (which is 5.5 located at 7th).

>I can do this:

>xlis = {0, 1, 3, 10, 4, 5, 5.5, 10.25};
>dropOuterBraces[lst_List] := StringTake[#1, {2,
>StringLength[#1] - 1}] &[
>ToString[lst]]; (* took from previous help posted by Peter Pein *)
>n1 = Nearest[xlis, 6]
>eval = dropOuterBraces[n1]
>Position[xlis, eval]
>Position[xlis, 5]

A one line solution to returning the desired position number is

Ordering[Abs[xlis-6],1][[1]]
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