On Mar 12, 2013, at 2:59 PM, Rajat Tayal <ra...@igidr.ac.in> wrote: > Dear list members, > > I am trying to fit a natural cubic spline to my dataset using the ns > function in the splines package. > Specifically, I do: > > library(splines) > lm(y ~ ns(x, df=3), data =data) > > How do I extract the values of the interior knots of the fitted spline ? > > Thanks, > > Rajat
Using the example from ?ns: require(splines) fm1 <- lm(weight ~ ns(height, df = 5), data = women) > attr(terms(fm1), "predvars") list(weight, ns(height, knots = c(60.8, 63.6, 66.4, 69.2), Boundary.knots = c(58, 72), intercept = FALSE)) or directly on the data: > attr(ns(women$height, df = 5), "knots") 20% 40% 60% 80% 60.8 63.6 66.4 69.2 > attr(ns(women$height, df = 5), "Boundary.knots") [1] 58 72 Regards, Marc Schwartz ______________________________________________ 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.
