From: [EMAIL PROTECTED] > > ronggui a écrit : > > > I think it is NOT just for historical reason. > > see the following example: > > > >>rm(x) > >>mean(x=1:10) > > [1] 5.5 > >>x > > Error: object "x" not found > > x is an argument local to mean(), > did you expect another answer ? > > >>mean(x<-1:10) > > [1] 5.5 > >>x > > [1] 1 2 3 4 5 6 7 8 9 10 > > What is the goal of this "example" ?
I believe it's to show why "<-" is to be preferred over "=" for assignment... > Here with "<-", > (voluntary, or not, side effect) > the global variable x is, also, created. > Did the writer really want that ??? Very much so, I believe. > I though there were other specific statements > especially intended for global assignment, eg "<<-". You need to distinguish assignment in function _call_ and assignment in function _definition_. They ain't the same. > If this example was intended to prove "<-" > is better than "=" > ... I'm not really convinced ! In that case, let's try another one (which is one big reason I stopped using "=" for assignment): > long.comp <- function(n) { + Sys.sleep(n) + n + } > result = long.comp(30) > system.time(result = long.comp(30)) Error in system.time(result = long.comp(30)) : unused argument(s) (result ...) > system.time(result <- long.comp(30)) [1] 0.00 0.00 30.05 NA NA > str(result) num 30 Cheers, Andy > ______________________________________________ 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