On Oct 16, 2014, at 10:36 PM, PO SU wrote:
Tks for your advice, let the ++ problem alone, how to write an Unary operator ? Is it permitted in R?such as a<-2 , a%+2% will let a be 4 .
OK, that's just wrong. Oh, OK, just for fun, as it were:
inc <- function(x)
{
eval.parent(substitute(x <- x + 1))
}
> inc(10)
Error in 10 <- 10 + 1 : invalid (do_set) left-hand side to assignment
> y=10
> inc(y)
> y
[1] 11
I just want to know it , i won't pollute r with it , because i know what is r . : )It's certainly permitted. Just look at all the overloadings of the "+" operator in graphics packages. Look up the documentation on methods in R.
Why not just use a well-behaved function, though? .inc <- function(x) x+1 > .inc(10) [1] 11Then you won't be tempted to try 10 <- .inc(10) because it just wouldn't make sense.
-- David.
-- PO SU mail: desolato...@163.com Majored in Statistics from SJTU At 2014-10-17 13:09:47, "Rolf Turner" <r.tur...@auckland.ac.nz> wrote:On 17/10/14 17:29, PO SU wrote:Dear expeRts,Now i want to know how to implement an Unary operator like i++ in cpp's synax form.e.g. 2++ will let 2 be 3 , a<-2 ,a++ ,will let a be 3 I tried this : '%++%'<-function(x){ x<<-x+1 } but it have problem, the biggest one is it seems the function needtwoparams like a%++%b , how to write a function needing just one param?TKS !Just ***DON'T***. The "++" operator is useful only for those wish to write code which is obscure to the point of incomprehensibility. It makes C and its offspring "write only" languages. If you are going to use R, use R and don't pollute it with such abominations. cheers, Rolf Turner -- Rolf Turner Technical Editor ANZJS______________________________________________ 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.
David Winsemius, MD Alameda, CA, USA ______________________________________________ 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.
