On Sun, Nov 4, 2012 at 6:35 AM, Justin Talbot <jtal...@stanford.edu> wrote: >> >> Then the case for psum is more for convenience and speed -vs- >> colSums(rbind(x,y), na.rm=TRUE)), since rbind will copy x and y into a new >> matrix. The case for pprod is similar, plus colProds doesn't exist. >> > > Right, and consistency; for what that's worth. > >>> Thus, + should have the signature: `+`(..., na.rm=FALSE), which would >>> allow you to do things like: >>> >>> `+`(c(1,2),c(1,2),c(1,2),NA, na.rm=TRUE) = c(3,6) >>> >>> If you don't like typing `+`, you could always alias psum to `+`. >> >> But there would be a cost, wouldn't there? `+` is a dyadic .Primitive. >> Changing that to take `...` and `na.rm` could slow it down (iiuc), and any >> changes to the existing language are risky. For example : >> `+`(1,2,3) >> is currently an error. Changing that to do something might have >> implications for some of the 4,000 packages (some might rely on that being >> an error), with a possible speed cost too. >> > > There would be a very slight performance cost for the current > interpreter. For the new bytecode compiler though there would be no > performance cost since the common binary form can be detected at > compile time and an optimized bytecode can be emitted for it. > > Taking what's currently an error and making it legal is a pretty safe > change; unless someone is currently relying on `+`(1,2,3) to return an > error, which I doubt. I think the bigger question on making this > change work would be on the S3 dispatch logic. I don't understand the > intricacies of S3 well enough to know if this change is plausible or > not. > >> In contrast, adding two functions that didn't exist before: psum and pprod, >> seems to be a safer and simpler proposition. > > Definitely easier. Leaves the language a bit more complicated, but > that might be the right trade off. I would strongly suggest adding > pany and pall as well. I find myself wishing for them all the time. > prange would be nice as well.
Have a look at the matrixStats package; it might bring what you're looking for: http://cran.r-project.org/web/packages/matrixStats /Henrik > > Justin > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
