Reading the list of changes for R version 2.4.0, I was happy to see that the row names of dataframes can be stored compactly (as the integer n when row.names(df) is 1:n).
help(row.names) contains this paragraph: Row names of the form '1:n' for 'n > 2' are stored internally in a compact form, which might be seen by calling 'attributes' but never via 'row.names' or 'attr(x, "row.names")'. I am unable to get attributes(x)$row.names to return just nrow(x). Am I misreading the documentation? Does "might be seen" mean "possibly in some future version of R" in this case? > (x <- as.data.frame(matrix(1:9, nrow=3))) V1 V2 V3 1 1 4 7 2 2 5 8 3 3 6 9 > attributes(x)$row.names [1] 1 2 3 > row.names(x) <- seq(len=nrow(x)) > attributes(x)$row.names [1] 1 2 3 Best, Hsiu-Khuern. ______________________________________________ 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.