I have a question about shallow copies in R. Since R 3.1.0, subsetting a dataframe with respect to its columns no longer result in deep copies. This is an amazing change in my opinion. Now, subsetting a data.frame by rows (or subsetting a matrix by columns or rows) still does deep copies. In particular, it is my understanding that running a command on a very large subset of rows (say "sum" or "biglm" on non outliers observations) results in a deep copy of these rows first, which can require twice as much the memory of the original data.frame/matrix. If this is correct, I would be very interested to know more on whether this behavior can/may change in future versions of R.
Thanks a lot!, Matthew ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
