--- Begin Message ---
This may be useful; convert them to NAs then omit them afterwards, you
end up keeping the positions where you had 0s.
> n[y==0] <- NA
> n
[1] 1 1 1 1 1 1 2 2 NA NA NA 2 3 3 NA NA 3 3
> na.omit(n)
[1] 1 1 1 1 1 1 2 2 2 3 3 3 3
attr(,"na.action")
[1] 9 10 11 15 16
attr(,"class")
[1] "omit"
HTH, Filipe
-----Mensagem original-----
De: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org]
Em nome de Duncan Murdoch
Enviada em: quarta-feira, 29 de junho de 2011 17:33
Para: Peter Maclean
Cc: r-help@r-project.org
Assunto: Re: [R] DROP OBSEVATION IN A GROUP
On 29/06/2011 4:29 PM, Peter Maclean wrote:
> People with more experience in R I need help on this.
> I would like to drop observation if they meet certain condition. In
this example
> I would like to drop group 2 in "n" because the group in "Y" has more
than 2
> zeroes.
> #Example
> n<- c(1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3,3)
> y<- c(2,3,2,3,4,5,6,1,0,0,0,6, 2, 1, 0, 0,9,3)
> z<- as.data.frame(cbind(n,y))
> colnames(z)<- c("n","y")
The general way to drop observations is to construct a logical vector to
use as an index. Entries which are FALSE are dropped.
Doing that based on your "more than 2 zeroes" rule looks a little
tricky; I think you want to count zeros first (e.g. using by()), then
construct the TRUE/FALSE vector based on that.
Duncan Murdoch
>
>
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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