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

[Peter Dalgaard]

"Gabor Grothendieck" <ggrothendieck at gmail.com> writes:

> 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++ .

It doesn't work infix. R allows arbitrary non-empty strings as object
names, with some syntax complications, but all I needed was a name
that could be passed to do.call....

 
> 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.
> >
> 

-- 
   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