Suppose I have two var x and y,now I want to fits a natural cubic spline in x to y,at the same time create new var containing the smoothed values of y. How can I get it?
If one enters:
??"spline"
... You get quite a few matches. The one in the stats functions that
probably answers your specific questions is:
"splinefun {stats} R Documentation
Interpolating Splines Description
Perform cubic (or Hermite) spline interpolation of given data points,
returning either a list of points obtained by the interpolation or a
function performing the interpolation."
"splinefun returns a function with formal arguments x and deriv, the
latter defaulting to zero. This function can be used to evaluate the
interpolating cubic spline (deriv=0), or its derivatives (deriv=1,2,3)
at the points x, where the spline function interpolates the data
points originally specified. This is often more useful than spline."
Perhaps you need to review from you basic intro material regarding
help.search("text") # or
??"text" # possibilities.
--
David Winsemius
On Mar 30, 2009, at 10:58 PM, minben wrote:
> Suppose I have two var x and y,now I want to fits a natural cubic
> spline in x to y,at the same time create new var containing the
> smoothed values of y. How can I get it?
>
> ______________________________________________
> 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.
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
Hello:
If B-splines will suffice, there are many capabilities in R for
that. My favorite is the 'fda' package, but 'splines' and other
packages are also good.
The "splinefun" function in the "base" package returns
a function
to compute spline interpolations optionally using a natural spline.
However, that is an interpolation spline and therefore does no smoothing.
To find other options for natural splines, I suggest you try the
CRAN packages splines, mboost, pspline, Design, and mgcv. I found them
using the "RSiteSearch" packages available from R-Forge via
'install.packages("RSiteSearch",
repos="http://r-forge.r-project.org")',
which also identified the "siggenes" package (which is not on CRAN).
I
don't know if any of these actually use natural splines, but this gives
you a reasonably short list to consider.
Hope this helps.
Spencer Graves
p.s. The following are the commands I used with the "RSiteSearch"
package:
library(RSiteSearch)
natSpl <- RSiteSearch.function('natural spline')
str(natSpl)
summary(natSpl)
natSpl[1:23, c(1, 4, 5, 7)]
minben wrote:> Suppose I have two var x and y,now I want to fits a natural cubic
> spline in x to y,at the same time create new var containing the
> smoothed values of y. How can I get it?
>
> ______________________________________________
> 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.
>
>