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MathGroup Archive 2007

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Re: Iterate Through a List

  • To: mathgroup at smc.vnet.net
  • Subject: [mg77367] Re: Iterate Through a List
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Thu, 7 Jun 2007 03:56:41 -0400 (EDT)
  • Organization: Uni Leipzig
  • References: <f4697t$3ps$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de

Hi,

try

First /@ MyListLooksLike

Regards
   Jens


Nick wrote:
> Hello! I'm (somewhat) new to Mathematica and I  need help to iterating
> through a list and counting the occurrence of a number.
> 
> My list looks like:
> 
> {{1,0},{1,1},{2,x+x^2+x^4},{2,1+x+x^2+x^4},{4,x+x^2},{4,1+x+x^2},{4,x+
> \
> x^4},{4,1+x+x^4},{4,x^2+x^4},{4,1+x^2+x^4},{4,x^3+x^4},{4,1+x^3+x^4},
> {\
> 4,x+x^2+x^3+x^4},{4,1+x+x^2+x^3+x^4},{5,x+x^3},{5,1+x+x^3},
> {5,x^2+x^3}\
> ,{5,1+x^2+x^3},{5,x+x^3+x^4},{5,1+x+x^3+x^4},{5,x^2+x^3+x^4},{5,1+x^2+
> \
> x^3+x^4},{8,x},{8,x^2},{8,x^3},{8,x^4},{8,1+x},{8,1+x^2},{8,1+x^3},
> {8,\
> x+x^2+x^3},{8,1+x+x^2+x^3},{8,1+x^4}}
> 
> The number that I would need to keep track of is the first in each sub-
> list.
> 
> So for the first couple {{1,0},{1,1},{2,x+x^2+x^4},{2,1+x+x^2+x^4},{4,x
> +x^2},........
> 
> I would need to keep track of 1,1,2,2,4........
> 
> It will not always be 1,2,4,5,8's.  The numbers may be completely
> different on each pass.  Each sublist may be composed of more items
> but the number that I need to keep track of will always be the 1st in
> the sub-list.  Any help or suggestions that you can give me will be
> greatly appreciated.  Thanks so much!
> -Nick
> 
> 


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