[R] sampling problem - new to R
Doran, Harold
HDoran at air.org
Wed Jun 6 15:56:42 CEST 2007
I dealt with something like this recently.
x <- data.frame(plot = gl(2,5), tree = rnorm(10))
y <- split(x, x$plot)
ss <- numeric(2)
for(i in 1:2){
ss[i] <- sample(row.names(y[[i]][1]), 1)
}
z <- x[ss,]
People help out of the goodness of the hearts and not for publication
recognition.
Harold
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of baldeck
> Sent: Tuesday, June 05, 2007 10:30 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] sampling problem - new to R
>
>
> I have a data set of individual trees and the plots that they are in:
>
> Tree Plot
> 56749 1
> 63494 1
> 87375 1
> 37494 2
> 92753 3
> 34847 3
> 38747 4 etc...
>
> So each plot is represented once for every individual that
> occurrs in it.
> Plots get different numbers of rows because there can be a
> different number of individuals in each plot.
>
> I want to make a data frame that consists of one individual
> from each plot.
> I would like to randomly choose one individual from each plot
> that is present in the data set. I will have to do this to
> multiple data sets which may contain different plots, and may
> contain up to 1200 plots, so I can't choose the plots by hand.
>
> Please help me with this. I'm an ecologist and I'm in
> Panama, with no one around who is educated in R. Whoever
> solves this problem for me will be acknowledged in any
> resulting publications.
>
> Thanks!
> -Claire
> --
> View this message in context:
> http://www.nabble.com/sampling-problem---new-to-R-tf3872130.ht
> ml#a10970708
> Sent from the R help mailing list archive at Nabble.com.
>
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