[R] do.call("+", ...)

[Peter Dalgaard]

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