Hi: To get the samples, here's one approach:
df <- data.frame(gender = rep(c('F', 'M'), c(165, 42)), y = rpois(207, 20)) # Sampling function to take 20 F and 20 M with replacement # The sample function operates on the rows of df to get idx and then takes # the y's corresponding to those rows sfun <- function(x) { idx <- c(sample(1:165, 20, replace = TRUE), sample(166:207, 20, replace = TRUE)) x[idx] } # Replicate the process 1000 times u <- t(replicate(1000, sfun(df$y))) > dim(u) [1] 1000 40 The first 20 rows are F, the second 20 M. HTH, Dennis On Thu, Mar 10, 2011 at 1:04 AM, taby gathoni <tab...@yahoo.com> wrote: > Please note is with replacement > > > > From: taby gathoni <tab...@yahoo.com> > To: R help <r-help@r-project.org> > Sent: Thursday, March 10, 2011 11:53 AM > Subject: [R] random sampling steps in R > > Dear all, > > Could someone assist me in random sampling steps/code in R? I have a main > sample of 42 males and 165 females and I want to come up with about 1000 > samples of 20 males and 20 females from this main sample. While at it, i > would also like to come up Accuracy Ratios (ARs) with corresponding > confidence intervals. > > Please assist. > > > Thanks so much, > > Taby > > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. > > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. > [[alternative HTML version deleted]] ______________________________________________ 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.