On Tue, Oct 16, 2018 at 12:03 AM Abs Spurdle <spurdl...@gmail.com> wrote:
> Probably the best example I can think of is converting cartesian > coordinates to polar coordinates. > Then we might have something like (note, untested, written in my email): > cart2polar = function (x, y) > list (theta=atan (y / x), r=sqrt (x * x + y * y) ) > > massign (r, theta) = cart2polar (x, y) > > Now, I'm considering a multiple assignment operator, so something like: > c (theta, r) $<-$ cart2polar (x, y) This is something that comes up occasionally and as noted by Gabor, has been implemented in packages. But I am not keen on unpacking the return from a function into multiple objects. The reason your `cart2polar` function returns a list of theta and r is because it is returning a polar coordinate, and that coordinate needs both. Why unpack them? If you don't need theta, then do `r = cart2polar(x,y)$r`. If you need theta and r, then keep them together in a single object. If you need to call a function that needs separate theta and r, use `plot(d$r, d$theta)`. Its a bit more typing but that's a false efficiency when you want code to be tidy and well-structured, and to convey meaning. `plot(this$r, this$theta)` is clearly a plot of something to do with `this`, and you can see that the r and the theta are coming from the same thing, whereas a `(r,theta) %=% foo(x,y)` some place and then `plot(r, theta)` somewhere else has broken the connection. Barry ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
