I was wondering if copies were made when a component of a complex nested list structure was extracted but not modified. I was happy that the answer was no, but was surprised that copies weren't made even if the extracted bit was modified:
> x <- list(a=list(b=numeric(1000000))) > y <- x[[c(1,1)]] > y[1] <- 3.14159 > x[[c(1,1)]][1] [1] 3.14159 Unfortunately, this exists in today's release of 2.8.1. I should have done this test last week! Duncan Murdoch > sessionInfo() R version 2.8.1 (2008-12-22) i386-pc-mingw32 locale: LC_COLLATE=English_United States.1252;LC_CTYPE=English_United States.1252;LC_MONETARY=English_United States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252 attached base packages: [1] stats graphics grDevices utils datasets methods base loaded via a namespace (and not attached): [1] tools_2.8.1 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
