On Thu, 10 Apr 2008, Kyeongmi Cheon wrote: > Hello list, > I found that system.time works correctly when I used "<-" to assign a > value to a variable but when I happened to use "=" instead of "<-", R > gave an error message: > "Error in system.time(your argument here...)". It happened with a few > functions I tried. Is this a bug or is there any circumstances that > "=" cannot be used for assignment? Here is a real simple example.
The latter. Although some might say the former, too. And some will no doubt flame me for even saying that. The former, I mean. Arguments in calls to function (aka arglists) can be in the name=object form. So, (function(x,y) x-y)(y=3,x=2) evaluates to -1, while (function(x,y) x-y)( 3, 2 ) evaluates to 1, as does (function(x,y) x-y)(me <- 3, you <- 2) but (function(x,y) x-y)(me = 3, you = 2) gives an error when it tries to match 'me' or 'you' to an argument but fails to find one. Hint: often system.time( { result.of.long.compute <- foo(my.args) } ) is what you want. HTH, Chuck p.s. As an exercise for the reader, why does (function(x,y) x-y)({me = 3},{you = 2}) not return an error? > > fn1 <- function(x) x+1 > > r1 <- system.time(res1=fn1(2)) > r2 <- system.time(res2 <- fn1(2)) > > > Thank you. > Kyeongmi > University of Memphis > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > Charles C. Berry (858) 534-2098 Dept of Family/Preventive Medicine E mailto:[EMAIL PROTECTED] UC San Diego http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901 ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.