On Tue, 2 Mar 2004 [EMAIL PROTECTED] wrote: > Apparently row names are dropped when I extract > single column from a data frame. Why this behaviour ? > > > y <- as.matrix(df[,1:2]); length(row.names(y)) > [1] 324 > > y <- as.matrix(df[,1:1]); length(row.names(y)) > [1] 0
Why are you converting a subsetted data frame to a matrix? df[, 1:2] is a data frame, and df[, 1:1] is a single column (most likely a vector). The latter is not going to have row names, but it might have names. It happens that in S the row names are not copied across as names. row.names applies to a data frame, and not to a matrix, strictly. -- 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 https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
