recursively divide a value to get a sequence
On Wed, 2008-07-09 at 11:40 +0200, 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.
Well, if you really want to do it recursively (and maybe loopy as well)
recursivdiv<-function(x,denom,lendiv,firstpass=TRUE) {
if(firstpass) lendiv<-lendiv-1
if(lendiv > 1) {
divvec<-c(x/denom,recursivdiv(x/denom,denom,lendiv-1,FALSE))
cat(divvec,ndiv,"\n")
}
else divvec<-0
if(firstpass) divvec<-c(x,divvec)
return(divvec)
}
Jim