Barry Rowlingson wrote: > Gustaf Rydevik wrote: >> Hi all, >> >> Reading the wikipedia page on R, I stumbled across the following: >> http://fluff.info/blog/arch/00000172.htm >> >> It does seem interesting that the C execution is that much slower from >> R than from a native C program. Could any of the more technically >> knowledgeable people explain why this is so? > > I don't think it is. He's comparing some C code with calling > fisher.test() from R, which he claims does 'nothing but call C code over > and over'. Wrong. It checks its arguments in R, it checks for multiple > arguments, it does all sorts of goodness before finally calling > .C("fexact"). And then it does even more things. Confidence intervals, > odds ratios, p-values and so on. > > He needs to re-run his tests but instead of calling fisher.test() he > should prepare the data and call .C("fexact",...) directly. > >> The author also have some thought-provoking opinions on R being >> no-good and that you should write everything in C instead (mainly >> because R is slow and too good at graphics, encouraging data >> snooping). See http://fluff.info/blog/arch/00000041.htm > > And of course C is good at buffer overflows and memory leaks and > spending ages compiling when you really just want to do fisher.test(foo) > and have done with it. > > He says: "I used to have a simulation written in R calling compiled C > that took overnight to process 100 agents, but now that it's all in C > simulations with 9,000 agents run in forty minutes. Don't risk it--learn > to do statistical computing in C today!". Fine, but I imagine his R code > was created much quicker than the C code. R is quicker to write, and > once you have established that your code is running too slow for you, > then you optimise. By that point you've hopefully debugged your > algorithm and spotted all the nasty traps that would have tied you up in > the C debugger for a week. You then rewrite in pure C for speed, and you > of course have a set of test cases generated from R to verify your C is > doing the same as your R. Win win. > > He claims to be an economist but clearly doesn't recognise the economy > of rapid development... > > Barry
If support list activity is any surrogate measure of the success of his arguments, that there are 7 subscribers and only 2 posts (both by the same person and without a reply from the application author) on the Apophenia e-mail lists at: https://sourceforge.net/mail/?group_id=130901 one would hypothesize that he has been less than persuasive... What color is the sky in his world? ;-) Regards, Marc Schwartz ______________________________________________ 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.
