Thanks. As a (relatively) new user of R and programming in general, I tend to miss things like that. I appreciate your patience.
SR Steven H. Ranney Graduate Research Assistant (Ph.D) USGS Montana Cooperative Fishery Research Unit Montana State University PO Box 173460 Bozeman, MT 59717-3460 phone: (406) 994-6643 fax: (406) 994-7479 -----Original Message----- From: Prof Brian Ripley [mailto:[EMAIL PROTECTED] Sent: Thu 6/12/2008 7:00 AM To: Ranney, Steven Cc: r-help@r-project.org Subject: Re: [R] Predicting from an nls model To predict from Weight~alpha*Length^beta you need to specify Length, not Weight. It is most likely finding Length from your workspace. On Thu, 12 Jun 2008, Ranney, Steven wrote: > I keep running up against the same error when I try to plot a line from a nls > model. The data is fisheries length/weight data. Code follows: > > require(graphics) > pow = nls(Weight~alpha*Length^beta, data=wae, > start=list(alpha=0.0000001, beta=3.0), trace=TRUE) > predict(pow) > plot(Weight~Length, data = wae, pch=19, > xlab="Length (mm)", ylab="Weight (g)", > xlim = c(150,1000), ylim = c(0, 10050)) > mod = seq(150, 1000) > lines(mod, predict(pow, list(Weight = mod))) > > The error I get after I submit the final line is: > > Error in xy.coords(x, y) : 'x' and 'y' lengths differ > > Like my last post, I'm certain there's something simple I'm overlooking. > I've been able to get this to work on other data sets, but _how_ I've been > able to get this to work, I'm unsure. > > Thanks for your help, > > SR > > Steven H. Ranney > Graduate Research Assistant (Ph.D) > USGS Montana Cooperative Fishery Research Unit > Montana State University > PO Box 173460 > Bozeman, MT 59717-3460 > > phone: (406) 994-6643 > fax: (406) 994-7479 > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 [[alternative HTML version deleted]] ______________________________________________ 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.
