[R] which operators are available? (was: Re: do.call("+", ...))

[Gabor Grothendieck]

I did not realize that ++ was available.  Is there a comprehensive list
somewhere of which operators are available for definition?  I searched
the R Language manual for ++ but that only came up with a reference to C++ .

On 17 Nov 2006 11:38:43 +0100, Peter Dalgaard <p.dalgaard at biostat.ku.dk> wrote:
> rfrancois at mango-solutions.com writes:
>
> > Hi,
> >
> > You could stack your list in an array and then use apply :
> >
> > myArray <- array( unlist(lapply(1:3, f) ) , dim =c(2, 3, 3))
> > apply(myArray, c(1,2), sum)
>
> Or fixup "+" to take more than two arguments, e.g.
>
> "++" <- function(x, ...) if (nargs() == 1) x else x + Recall(...)
>
> f  <- function(i){matrix((1:6)^i, 2, 3)}
> do.call("++", sapply(1:4, f, simplify=FALSE))
>
> ##
>
> > "++" <- function(x, ...) if (nargs() == 1) x else x + Recall(...)
> > f  <- function(i){matrix((1:6)^i, 2, 3)}
> > do.call("++", sapply(1:4, f, simplify=FALSE))
>     [,1] [,2] [,3]
> [1,]    4  120  780
> [2,]   30  340 1554
>
>
>
>
> > Cheers,
> >
> > Romain
> >
> > Quoting Robin Hankin <r.hankin at noc.soton.ac.uk>:
> >
> > > Hi
> > >
> > > How do I make do.call() take "+" as a function for a list of more
> > > than two elements?
> > >
> > > Toy problem follows:
> > >
> > >
> > > f  <- function(i){matrix((1:6)^i,2,3)}
> > >
> > > # Thus f() returns a matrix of size 2x3; I want to add a whole bunch
> > > of such matrices,
> > > # as in  f(1) + f(2) + f(3) + f(4)
> > >
> > > # But:
> > >
> > >
> > >
> > >  > do.call("+",sapply(1:4,f,simplify=FALSE))
> > > Error in do.call("+", sapply(1:4, f, simplify = FALSE)) :
> > >     operator needs one or two arguments
> > >
> > >
> > >
> > >
> > > Also,
> > >
> > >
> > >  > do.call(sum,sapply(1:4,f,simplify=FALSE))
> > > [1] 2828
> > >
> > >
> > > doesn't do what I want (I would like a 2x3 matrix whose elements are the
> > > sum of corresponding elements in my list)
> > >
> > > How to do this nicely?
> > >
> > >
> > >
> > >
> > >
> > > --
> > > Robin Hankin
> > > Uncertainty Analyst
> > > National Oceanography Centre, Southampton
> > > European Way, Southampton SO14 3ZH, UK
> > >   tel  023-8059-7743
> > >
> > > ______________________________________________
> > > R-help at 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
> > > and provide commented, minimal, self-contained, reproducible code.
> > >
> >
> > ______________________________________________
> > R-help at 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
> > and provide commented, minimal, self-contained, reproducible code.
> >
>
> --
>   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
>  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
>  (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
> ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907
>
> ______________________________________________
> R-help at 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
> and provide commented, minimal, self-contained, reproducible code.
>