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
---------------------------------
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As reported in ?spline, you should use splinefun() instead. ff<-splinefun(x,y) ff(x0) where x0=5.25 is your case. best, vito stat stat ha scritto:> 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 at 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. > >-- ===================================Vito M.R. Muggeo Dip.to Sc Statist e Matem `Vianelli' Universit? di Palermo viale delle Scienze, edificio 13 90128 Palermo - ITALY tel: 091 6626240 fax: 091 485726/485612
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: r-help-bounces at r-project.org
[mailto:r-help-bounces at r-project.org]On Behalf Of stat stat
Sent: 05 October 2007 09:31
To: r-help at stat.math.ethz.ch
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 at 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.