I understand R is a "Pass-By-Value" language. I have a few practical questions, however.
I'm dealing with a "large" dataset (~1GB) and so my understanding of the nuances of memory usage in R is becoming important. In an example such as: > d <- read.csv("file.csv"); > n <- apply(d, 1, sum); must "d" be copied to another location in memory in order to be used by apply? In general, is copying only done when a variable is updated within a function? Would the following example be any different in terms of memory usage? > d <- read.csv("file.csv"); > n <- apply(d[,2:10], 1, sum); or can R reference the original "d" object since no changes to the object are being made? I'm familiar with FF and BigMemory, but are there any packages/tricks which allow for passing such objects by reference without having to code in C? Regards, Jeff Allen ______________________________________________ R-help@r-project.org 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.