generating a sequence
"Jens Oehlschl?gel-Akiyoshi" <jens.oehlschlaegel-akiyoshi at mdfactory.de> writes:
As this looks like a funny performance competition,
here a very tricky algorithm I once received from Angelo Canty
vecseq <- function(x,y=NULL) {
# x1:y1,x2:y2 ... Angelo Canty 8/97
# parameter handling (c) JOA 1997
if (missing(y)) {y <- x; x <- 1}
if (length(y)==1) y <- rep(y,length(x))
if (length(x)==1) x <- rep(x,length(y))
str <- paste("c(",paste(x,y,sep=":",collapse=","),")")
eval(parse(text=str))
}
....
So, vecsec() is more flexible and much faster than R's sequence, why not redefine sequence ? (timings on PII 400 NT4.0)
Hmm. vecseq is certainly impressively fast, but I tend to find any routine that involves parsing suspicious. sequence<-function(nvec)unlist(lapply(nvec,function(x)1:x)) clocks in at 0.09 (if you gc() first) and would seem to be equivalent to the current one. Still two times slower than vecseq, though...
O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._