smooth.spline is a handy function and does what you need: Careful to not over fit though. Use different values of spar and df.
y<-c(467, 468, 460 ,460 ,450, 432, 419, 420, 423, 423) x<-1:10 plot(x,y) predict(smooth.spline(x,y,df=4),x=3.5) lines(predict(smooth.spline(x,y,df=4),x=seq(1,10,length=100)),col="red",lwd=2) lines(predict(smooth.spline(x,y,df=8),x=seq(1,10,length=100)),col="red",lwd=2) -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of stat stat Sent: 05 October 2007 09:31 To: [EMAIL PROTECTED] Subject: [R] Splines I want to fit a cubic spline of x on y. where : x [1] 467 468 460 460 450 432 419 420 423 423 y [1] 1 2 3 4 5 6 7 8 9 10 using the syntax spline(y, x) I got following output : $x [1] 1.000000 1.310345 1.620690 1.931034 2.241379 2.551724 2.862069 [8] 3.172414 3.482759 3.793103 4.103448 4.413793 4.724138 5.034483 [15] 5.344828 5.655172 5.965517 6.275862 6.586207 6.896552 7.206897 [22] 7.517241 7.827586 8.137931 8.448276 8.758621 9.068966 9.379310 [29] 9.689655 10.000000 $y [1] 467.0000 469.5381 469.8643 468.4865 465.9444 463.0284 460.6479 459.6560 [9] 459.8737 460.2296 459.6313 457.4921 454.0094 449.4482 444.1040 438.3613 [17] 432.6204 427.2892 422.8183 419.6733 418.2646 418.3633 419.3283 420.5202 [25] 421.5768 422.4555 423.1312 423.5419 423.5480 423.0000 Now I want to get what is the value of y at x = 5.25. Can anyone tell me how to find that? thanks in advance --------------------------------- Meet people who discuss and share your passions. Join them now. [[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. ______________________________________________ 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.