Another alternative is to use the underappreciated function 'sweep()': sweep(A, 1:2, a, "+")
Internally this is about the same as your 'A + array(a, c(2,2,2))'. But it has the advantage that it makes explicit what the relationship between the dimensions of 'A' and 'a' is. I find that relying on implicit recycling tends to produce errors that are hard to trace, and code that is hard to understand six months later. Rich Raubertas Merck & Co. > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Prof > Brian Ripley > Sent: Wednesday, March 31, 2004 10:00 AM > To: Tamas Papp > Cc: R-help mailing list > Subject: Re: [R] array addition doesn't recycle! > > > The recycling rules are documented and this is not amongst them. > Computer packages do have a tendency to follow their rules > rather than > read your mind. > > I suspect A + as.vector(a) is what you intended. > > On Wed, 31 Mar 2004, Tamas Papp wrote: > > > Hi, > > > > I have noticed the following: > > > > > a <- array(1:4, c(2, 2)) > > > A <- array(1:4, c(2,2,2)) > > > A + a > > Error in A + a : non-conformable arrays > > > > It works with a matrix + a vector, why doesn't it work with arrays? > > Am I missing something? > > > > How would you do the above operation efficiently (ie I need to add a > > matrix to each "plane" of 3-dim array)? At the moment I am using > > something like > > > > A + array(a, c(2,2,2)) > > > > but it doesn't seem that efficient. > > Why do you think is `not that efficient'? Does you have a > need to save > microseconds? > > -- > Brian D. Ripley, [EMAIL PROTECTED] > Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ > University of Oxford, Tel: +44 1865 272861 (self) > 1 South Parks Road, +44 1865 272866 (PA) > Oxford OX1 3TG, UK Fax: +44 1865 272595 > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
