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

• To: mathgroup at smc.vnet.net
• Subject: [mg4542] Re: How do I use Select[list,condition]?
• From: Harald Berndt <haraldb at nature.berkeley.edu>
• Date: Wed, 7 Aug 1996 04:17:48 -0400
• Organization: University of California Forest Products Lab
• 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?

The syntax and use of pure functions in Mathematica took me a while to
get used to, but it was (is) well worth the effort. You came close,
but forgot some things. It will work if you write it like this:

In[5]:=
Select[ data, (#[[2]] == 2)& ]
Out[5]=
{{1, 2, b, 4, 5, 6}, {2, 2, b, 2, 3, 4}, {3, 2, b, 7, 8, 9}}
--
_______________________________________________________________
Harald Berndt                          University of California
Research Specialist                  Forest Products Laboratory
Phone: 510-215-4224                            FAX:510-215-4299
_______________________________________________________________

==== [MESSAGE SEPARATOR] ====

```

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