On Mon, Jun 24, 2013 at 4:27 PM, David Kulp <dk...@fiksu.com> wrote: > According to > http://cran.r-project.org/doc/contrib/Fox-Companion/appendix-scope.pdf and > other examples online, I am to believe that R resolves variables using > lexical scoping by following the frames up the call stack. However, that's > not working for me. For example, the following code, taken from the > reference above fails instead of returning 7. What am I doing wrong? Thanks! > > f <- function(x) { a<-5; g(x) } > g <- function(y) { y + a } > f(2) > Error in g(x) : object 'a' not found >
What you have described is called dynamic scoping. What lexical scoping is is that it resolves free variables based on where the function is _defined_, not where it is run and it has nothing to do with the call stack. a is a free variable in g and so when g is run R looks up a in the environment where g was defined which is the global environment and there is no a there. -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com ______________________________________________ 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.
