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Topic: How do I use Select[list,condition]?
Replies: 7   Last Post: Aug 2, 1996 2:04 AM

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Harald Berndt

Posts: 24
Registered: 12/7/04
Re: How do I use Select[list,condition]?
Posted: Jul 30, 1996 3:02 AM
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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:

Select[ data, (#[[2]] == 2)& ]
{{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

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