On Tue, 2007-08-14 at 07:48 -0400, Benjamin Tyner wrote: > Why not > > hasNA <- function(x) !is.na(match(NA, x)) > > -Ben
It does not save anything: Vec1 <- c(NA, rep(1, 10000000)) Vec2 <- c(rep(1, 10000000), NA) > system.time(!is.na(match(NA, Vec1))) user system elapsed 1.053 0.217 1.404 > system.time(!is.na(match(NA, Vec2))) user system elapsed 1.049 0.242 1.360 Note, there is no difference in execution time between the two. Review the source code for match() in unique.c and you will see why. Now try: > system.time(any(is.na(Vec1))) user system elapsed 0.242 0.079 0.358 > system.time(any(is.na(Vec2))) user system elapsed 0.255 0.067 0.321 Still essentially no time difference, but notably faster than using match(). To get much faster, you would likely need to code a new function in C, patterned after Kurt's reply. HTH, Marc Schwartz ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
