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MathGroup Archive 1996

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Re: How do I use Select[list,condition]?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg4569] Re: How do I use Select[list,condition]?
  • From: Hein Hundal <hundal at vicon.net>
  • Date: Fri, 16 Aug 1996 05:15:03 -0400
  • Organization: Core Capital
  • Sender: owner-wri-mathgroup at wolfram.com

Jason Welter wrote:
> 
> I have a list that looks like:
> 
> data = {{1,1,a,4,5,6},{2,1,a,2,3,4},{3,1,a,7,8,9},
>                {1,2,b,4,5,6},{2,2,b,2,3,4},{3,2,b,7,8,9},
>                {1,3,c,4,5,6},{2,3,c,2,3,4},{3,3,c,7,8,9}}
> 
> and I want to pick out the lists that have a 2 as the second element
> of the list.  I tried something like:
> 
> data1 = Select[data,data[[#,2]]==2];
> 
> but this doesn't work.  How do I do it?

Jason, you have two problems.
   1) You forgot the & at the end of your pure function.
   2) You included 'data' in your pure function definition.  
   
Place the # where the input to your pure function should be and then it 
works.

Select[data, #[[2]]==2 &]
{{1, 2, b, 4, 5, 6}, {2, 2, b, 2, 3, 4}, {3, 2, b, 7, 8, 9}}

Hope that works for you.  Hein Hundal.

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