From: bunny, lautloscrew.com > > Dear all, > > i am stuck with a syntax problem. > > i have a matrix which has about 500 rows and 6 columns. > now i want to kick some data out. > i want create a new matrix which is basically the old one > except for all entries which have a 4 in the 5 column AND a 1 > in the 6th column. > > i tried the following but couldnĀ“t get a new matrix, just some wierd > errors: > > newmatrix=oldmatrix[,2][oldmatrix[,5]==4]&&oldmatrix[,2][oldmatrix[,6] > ==1] > > all i get is: > numeric(0)
That's not a `weird error', but a numeric vector of length 0. > does anybody have an idea how to fix this one ? Try: newmatrix = oldmatrix[oldmatrix[, 5]==4 & oldmatrix[, 6] == 1, 2, drop=FALSE] If you just want a subset of column 2 as a vector, you can leave off the drop=FALSE part. Reading "An Introduction to R" should have save you some trouble in the first place. Andy > thx in advance > > matthias > [[alternative HTML version deleted]] > > ------------------------------------------------------------------------------ Notice: This e-mail message, together with any attachments,...{{dropped}} ______________________________________________ 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.