Full_Name: Jonathan Swinton Version: 2.2.1 OS: Windows Submission from: (NULL) (193.132.159.169)
#The first line of description for data.matrix says that it will # 'Return the matrix obtained by converting all the variables in a # data frame to numeric mode and then binding them together as the # columns of a matrix.' #However when called with a data.frame with zero rows, data.matrix returns a matrix #of mode logical rather than numeric. This conflicts with the documentation #and is not what seems sensible. # One underlying reason for this is that when a zero-length column of a matrix of mode logical is # asserted to be numeric the matrix is not actually cast to numeric. I wonder if that too is a bug? > R.version.string [1] "R version 2.2.1, 2005-12-20" > df <- data.frame(matrix(1:2,nrow=2)) > mode(data.matrix(df)[,1]) [1] "numeric" > mode(data.matrix(df[FALSE,])[,1]) [1] "numeric" > > # Underlying cause > x <- matrix(nr = 2,nc = 1 ) > mode(x) [1] "logical" > x[, 1] <- c(1,2) > mode(x) [1] "numeric" > > x0 <- matrix(nr = 0, nc = 1) > x0[, 1] <- numeric(0) > mode(x0) [1] "logical" > mode(x0[,1]) [1] "logical" ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
