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MathGroup Archive 2007

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Re: Finding position of an element in a list:

  • To: mathgroup at smc.vnet.net
  • Subject: [mg84022] Re: Finding position of an element in a list:
  • From: Tom Burton <news at brahea.com>
  • Date: Thu, 6 Dec 2007 07:29:12 -0500 (EST)

It should be clear to you that dropOuterBraces returns a string.  
There are no strings in your list, so of course Position returns the  
empty set. By default, Mathematica does not quote outputed strings,  
allowing your confusion. To avoid future confusion, you can in the  
Options Inspector set the global parameter

ShowStringCharacters -> True

You could modify dropOuterBraces to yield a number (see  
ToExpression), however, it's far easier to do this:

eval = First[n1]

Tom

When responding, please replace news with my first initial and full  
last name, as one word.

Tom Burton

> ... 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]...






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