On 5/22/2006 5:01 PM, ivo welch wrote: > Hi Thomas: > >> One case where the vector-vector recycling rules are used is in >> vector-matrix operations: >> a<-1:4 >> b<-diag(4) >> a+b > > is this last expression intended to be intuitive and thus desirable? > if anything else, I would end up writing something like this more as > an error than by intent. I would suggest that recycling might be > better to be explicitly asked for by the user---though I am not sure > what the syntax should be. > allow.recycle(a+b) > at the end, I think implicit recycling is a tradeoff between > convenience and unintended errors. I would judge the convenience of > implicit recycling to be fairly low, and the unintended error rate > [with difficulty finding it] to be fairly high. > > I guess the R language has few options() that control its > behavior---e.g., ala "use strict;" in perl. If it did, I would love > to turn off implicit recycling, provided there is an explicit recycle > possibility.
While I agree with you about these things in principle, this is a very old S design decision, and I think it can't really change now. It would have to be a local change (i.e. "in my namespace, do things strictly"), and that's very unlikely to happen. I would not mind having the ability to be forced to > define variables first, either, though this is not a big deal. R is > pretty good in telling me when I use variables that have not been > defined. There are some code tools around that help to detect such things. Duncan Murdoch ______________________________________________ R-help@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