Re: How do I use Select[list,condition]?
- To: mathgroup at smc.vnet.net
- Subject: [mg4528] Re: How do I use Select[list,condition]?
- From: Stephen P Luttrell <luttrell at signal.dra.hmg.gb>
- Date: Wed, 7 Aug 1996 04:17:36 -0400
- Organization: Defence Research Agency, Malvern
- 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?
Try the following:
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}};
Select[data, MatchQ[#, {_,2,___}]&]
which produces the output
{{1, 2, b, 4, 5, 6}, {2, 2, b, 2, 3, 4}, {3, 2, b, 7, 8, 9}}
--
Dr Stephen P Luttrell luttrell at signal.dra.hmg.gb
Adaptive Systems Theory 01684-894046 (phone)
Room EX21, Defence Research Agency 01684-894384 (fax)
Malvern, Worcs, WR14 3PS, U.K. http://www.dra.hmg.gb/cis5pip/Welcome.html
==== [MESSAGE SEPARATOR] ====