From: bartjoosen <bartjoosen_at_hotmail.com>

Date: Wed, 09 Jul 2008 03:36:59 -0700 (PDT)

x[length(x)] <- 0

return(x)

}

Date: Wed, 09 Jul 2008 03:36:59 -0700 (PDT)

Maybe something like this:

f1 with loop, f2 without.

f1 <- function(start,len, div) {

x <- rep(start,len)

for (i in 2 : (len-1)) {

x[i] <- x[i-1]/div

}

x[len] <- 0

return(x)

}

f2 <- function(start,len, div) {

x <- rep(start,len) y <- div^(0:(len-1)) x <- x/y

x[length(x)] <- 0

return(x)

}

system.time(f1(10000,100000,0.5))

system.time(f2(10000,100000,0.5))

Best regards

Bart

Anne-Marie Ternes wrote:

*>
**> Hi,
**>
*

> if given the value of, say, 15000, I would like to be able to divide

*> that value recursively by, say, 5, and to get a vector of a determined
**> length, say 9, the last value being (set to) zero- i.e. like this:
**>
**> 15000 3000 600 120 24 4.8 0.96 0.192 0
**>
**> These are in fact concentration values from an experiment. For my
**> script, I get only the starting value (here 15000), and the factor by
**> which concentration is divided for each well, the last one having, by
**> definition, no antagonist at all.
**>
**> I have tried to use "seq", but it can "only" do positive or negative
**> increment. I didn't either find a way with "rep", "sweep" etc. These
**> function normally start from an existing vector, which is not the case
**> here, I have only got a single value to start with.
**>
**> I suppose I could do something "loopy", but I'm sure there is a better
**> way to do it.
**>
**> Thanks a lot for your help, hope the question is not too dumb...
**>
**> Anne-Marie
**>
**> ______________________________________________
**> R-help_at_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.
**>
**>
*

-- View this message in context: http://www.nabble.com/recursively-divide-a-value-to-get-a-sequence-tp18358046p18358674.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help_at_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.Received on Wed 09 Jul 2008 - 11:05:35 GMT

Archive maintained by Robert King, hosted by
the discipline of
statistics at the
University of Newcastle,
Australia.

Archive generated by hypermail 2.2.0, at Wed 09 Jul 2008 - 11:31:49 GMT.

*
Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help.
Please read the posting
guide before posting to the list.
*