On 01/08/2015 01:30 PM, peter dalgaard wrote:
If you look at the definition of %in%, you'll find that it is implemented using match, so if we did as you suggest, I give it about three days before someone suggests to inline the function call...
But you wouldn't bet money on that right? Because you know you would loose.
Readability of source code is not usually our prime concern.
Don't sacrifice readability if you do not have a good reason for it. What's your reason here? Are you seriously suggesting that inlining makes a significant difference? As Michael pointed out, the expensive operation here is the hashing. But sadly some people like inlining and want to use it everywhere: it's easy and they feel good about it, even if it hurts readability and maintainability (if you use x %in% y instead of the inlined version, the day someone changes the implementation of x %in% y for something faster, or fixes a bug in it, your code will automatically benefit, right now it won't). More simply put: good readability generally leads to better code.
The && idea does have some merit, though. Apropos, why is there no setcontains()?
Wait... shouldn't everybody use all(match(x, y, nomatch = 0L) > 0L) ? H.
-pdOn 06 Jan 2015, at 22:02 , Hervé Pagès <hpa...@fredhutch.org> wrote: Hi, Current implementation: setequal <- function (x, y) { x <- as.vector(x) y <- as.vector(y) all(c(match(x, y, 0L) > 0L, match(y, x, 0L) > 0L)) } First what about replacing 'match(x, y, 0L) > 0L' and 'match(y, x, 0L) > 0L' with 'x %in% y' and 'y %in% x', respectively. They're strictly equivalent but the latter form is a lot more readable than the former (isn't this the "raison d'être" of %in%?): setequal <- function (x, y) { x <- as.vector(x) y <- as.vector(y) all(c(x %in% y, y %in% x)) } Furthermore, replacing 'all(c(x %in% y, y %in x))' with 'all(x %in% y) && all(y %in% x)' improves readability even more and, more importantly, reduces memory footprint significantly on big vectors (e.g. by 15% on integer vectors with 15M elements): setequal <- function (x, y) { x <- as.vector(x) y <- as.vector(y) all(x %in% y) && all(y %in% x) } It also seems to speed up things a little bit (not in a significant way though). Cheers, H. -- Hervé Pagès Program in Computational Biology Division of Public Health Sciences Fred Hutchinson Cancer Research Center 1100 Fairview Ave. N, M1-B514 P.O. Box 19024 Seattle, WA 98109-1024 E-mail: hpa...@fredhutch.org Phone: (206) 667-5791 Fax: (206) 667-1319 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
-- Hervé Pagès Program in Computational Biology Division of Public Health Sciences Fred Hutchinson Cancer Research Center 1100 Fairview Ave. N, M1-B514 P.O. Box 19024 Seattle, WA 98109-1024 E-mail: hpa...@fredhutch.org Phone: (206) 667-5791 Fax: (206) 667-1319 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
