I can feel a sermon coming on... I'd like to emphasize Martin's warning below and encourage you to avoid this kind of construction. The problem is side effects. Some R functions do this (e.g. fix) but everyone understands why. The real problem, in my view, is deeper. The question you ask originally implies that you don't really want a function, you want a macro. R does not work comfortably with macros, it works with functions.
This in turn suggests to me you are trying to make R work like some other software environment, presumably one with which you are familiar. This is very understanble, but nearly always a bad thing. If you are new to R, as you say, I would encourage you to find out how R works and work with it, rather than try to may R work the way you would like it to do. You will always be fighting the system unless you do. Here endeth the sermon. Bill Venables. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Martin Elff Sent: Wednesday, 6 February 2008 2:23 AM To: r-help@r-project.org Subject: Re: [R] modifying arrays within functions On Tuesday 05 February 2008 (16:51:41), Konrad BLOCHER wrote: > Hi, > > I'm pretty new to R and seem to be having difficulties with writing a > function that would change an array and keep the change after the function > finishes its work. > It seems you want this: X<-array(1,dim=c(2,2)) addition<-function(a){ X[1,1] <<- X[1,1]+a # not '=' } addition(1) X [,1] [,2] [1,] 2 1 [2,] 1 1 Nevertheless I would advise against writing and using functions that have side effects outside their scope. It is in general dangerous. Best, Martin ______________________________________________ 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. ______________________________________________ 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.
