On Mon, Mar 26, 2012 at 07:48:07PM -0400, Aimee Jones wrote: > Dear all, > > I'm aware if y has two separate functions (depending on the conditions > of x) you can use the ifelse function to separate y into two separate > functions depending on input. How do you do this if there a multiple > different conditions for x? > > for example, > > y fits the following between t>0 & t<15----->function(t) t^2, y fits > the following between t>15 & t<30-----> function(t) t^3, y fits the > following between t>30 &t<45--->function(t) t^4 etc
Hi. Try the following. bounds <- c(0, 15, 30, 45) x <- seq(4, 44, length=51) valfunc <- cbind(x^2, x^3, x^4) indfunc <- findInterval(x, bounds) y <- valfunc[cbind(1:nrow(valfunc), indfunc)] # verify range(x[y == x^2]) # [1] 4.0 14.4 range(x[y == x^3]) # [1] 15.2 29.6 range(x[y == x^4]) # [1] 30.4 44.0 Hope this helps. Petr Savicky. ______________________________________________ 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.
