R help - Aug 2009 - Smart way to sum a column in a matrix across all members in a list

Hi,

I have a list that contains about 100 elements. Each element contains
the following matrix structure

  a b
1 1 4
2 2 5
3 3 6

I'd like to sum column b across all elements. I'm thinking of using
lapply or sapply but cannot get it to work. Any help would be really
appreciated. Thank you.

adschai

Try this:

sum(sapply(l, '[[', 'b'))



On Tue, Aug 11, 2009 at 11:05 PM, R_help Help <rhelpacc@gmail.com> wrote:
> Hi,
>
> I have a list that contains about 100 elements. Each element contains
> the following matrix structure
>
>  a b
> 1 1 4
> 2 2 5
> 3 3 6
>
> I'd like to sum column b across all elements. I'm thinking of using
> lapply or sapply but cannot get it to work. Any help would be really
> appreciated. Thank you.
>
> adschai
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

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