Anup Nandialath wrote: > Dear Friends, > > I have a matrix of size 5000 X 20. The first two columns are indicator > variables taking the value of either 0 or 1. Let us call the first two > columns Y1 and Y2. > > I need to randomly sample 1000 rows with all the associated columns, in other > words my new matrix should be of size 1000 X 20. I realize that using this > command > > newmat <- mainmat[sample(1000,replace=F),] > > achieves this. However, I would like to make sure that both Y1 and Y2 have > more or less an equal amount of 0's and 1's. At present when I sample, I get > cases where sometimes all my Y2's are 0. Is there any way to accomodate this > problem.
Yes, for example drawing samples stratified by the values of Y1 or Y2. Uwe Ligges > Thanks in advance. > > Regards > > Anup > > > --------------------------------- > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@stat.math.ethz.ch 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. ______________________________________________ R-help@stat.math.ethz.ch 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.
