On Mon, 27 Jan 2003, Robert Schick wrote: > I'm using R 1.6.2 on Windows 2000. > > I have two similar sets of files in two different directories. One > contains species presence data and environmental measurements; the other > contains species absence data and environmental measurements for the > same variables as the presence data. > > The absence datasets contain many more observations than the presence > datasets, and I'd like to draw a random sample from these larger > datasets upon import of the text files. I would also like to condition > the import so that I only draw rows whose column(s) satisfy a criteria, > e.g. where data$temp <= 0. However, I'm not seeing anyway of doing this. > > I know I can use something like: > > > test <- read.table(file="10.06.94ed.txt",header=T) > > test2 <- test[test$temp>15,] > > test2[sort(sample(10)),] > > but can I do this as I read in the file? If yes, how could I find the # > of lines in my smaller file, and then pass that number to the sample > call on the larger file? (Is there a wc -l equivalent in R?)
?count.fields -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help