Yes, I had fixed that on my end but didn't notice I had copied the old version. I think its obvious enough that anyone will fix it themselves. Regards.
On Sat, Apr 7, 2012 at 7:23 PM, Rolf Turner <rolf.tur...@xtra.co.nz> wrote: > > One other minor glitch I just noticed: > > x <- seq_along(x) > > should read > > x <- seq_along(y) > > cheers, > > Rolf > > > On 08/04/12 10:08, Gabor Grothendieck wrote: >> >> On Sat, Apr 7, 2012 at 3:58 PM, Gabor Grothendieck >> <ggrothendi...@gmail.com> wrote: >>> >>> On Fri, Apr 6, 2012 at 9:42 PM, help ly<help.ly2...@gmail.com> wrote: >>>> >>>> Dear All, >>>> >>>> I would like to make a quadratic with a plateau model in R. Is there a >>>> package in R doing this? The bentcableAR package seems won't work. >>>> >>>> The link below describes what I am looking for in R exactly: >>>> >>>> http://support.sas.com/documentation/cdl/en/statug/63033/HTML/default/viewer.htm#statug_nlin_sect033.htm >>>> >>> Use nls directly: >>> >>> y<- c(0.46, 0.47, 0.57, 0.61, 0.62, 0.68, 0.69, 0.78, 0.7, 0.74, >>> 0.77, 0.78, 0.74, 0.8, 0.8, 0.78) >>> x<- seq_along(x) >>> >>> Mean<- function(x, alpha, beta, gamma) { >>> pmin(alpha + beta*x + gamma*x*x, alpha - beta^2/(4 * gamma)) >>> } >>> fm<- nls(y ~ Mean(x, alpha, beta, gamma), start = list(alpha = 0.45, >>> beta = 0.05, gamma = -0.0025)) >>> fm >>> summary(fm) >>> >>> plot(y ~ x) >>> lines(fitted(fm) ~ x) >> >> It was pointed out to me offline that Mean as defined above is not >> identical to the definition in the poster's link. Here is a revision: >> >> y<- c(0.46, 0.47, 0.57, 0.61, 0.62, 0.68, 0.69, 0.78, 0.7, 0.74, >> 0.77, 0.78, 0.74, 0.8, 0.8, 0.78) >> x<- seq_along(x) >> >> Mean<- function(x, alpha, beta, gamma) { >> ifelse(x< -beta/(2 * gamma), alpha + beta*x + gamma*x*x, >> alpha - beta^2/(4 * gamma)) >> } >> fm<- nls(y ~ Mean(x, alpha, beta, gamma), start = list(alpha = 0.45, >> beta = 0.05, gamma = -0.0025)) >> fm >> summary(fm) >> >> plot(y ~ x) >> lines(fitted(fm) ~ x) >> with(as.list(coef(fm)), abline(v = -beta/(2 * gamma))) >> >> > -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com ______________________________________________ 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.
