Re: [R] smooth.spline

From: Spencer Graves <spencer.graves_at_pdf.com>
Date: Fri, 18 Jul 2008 08:28:31 -0700

      PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.

      I do NOT know how to do what you want, but with a self-contained example, I suspect many people on this list -- probably including me -- could easily solve the problem. Without such an example, there is a high probability that any answer might (a) not respond to your need, and (b) take more time to develop, just because we don't know enough of what you are asking.

      Spencer

rkevinburton_at_charter.net wrote:
> Like I indicated. I understand the coefficients in a B-spline context. If I use the the 'spline' or 'splinefun' I can get the coefficients and they are grouped as 'a', 'b', 'c', and 'd' coefficients. But the coefficients for smooth.spline is just an array. I basically want to take these coefficients and outside of 'R' use them to form an interpolation. In other words I want 'R' to do the hard work and then export the results so they can be used else where.
>
> Thank you.
>
> Kevin
>

Spencer Graves wrote:
> I believe that a short answer to your question is that the
> "smooth" is a linear combination of B-spline basis functions, and the
> coefficients are the weights assigned to the different B-splines in
> that basis.
> Before offering a much longer answer, I would want to know what
> problem you are trying to solve and why you want to know. For a brief
> description of B-splines, see
> "http://en.wikipedia.org/wiki/B-spline". For a slightly longer
> commentary on them I suggest the "scripts\ch01.R" in the DierckxSpline
> package: That script computes and displays some B-splines using
> "splineDesign", "spline.des" in the 'splines' package plus comparable
> functions in the 'fda' package. For more info on this, I found the
> first chapter of Paul Dierckx (1993) Curve and Surface Fitting with
> Splines (Oxford U. Pr.). Beyond that, I've learned a lot from the
> 'fda' package and the two companion volumes by Ramsay and Silverman
> (2006) Functional Data Analysis, 2nd ed. and (2002) Applied Functional
> Data Analysis (both Springer).
> If you'd like more help from this listserve, PLEASE do read the
> posting guide http://www.R-project.org/posting-guide.html and provide
> commented, minimal, self-contained, reproducible code.
> Hope this helps. Spencer Graves
>
> rkevinburton_at_charter.net wrote:
>> I like what smooth.spline does but I am unclear on the output. I can
>> see from the documentation that there are fit.coef but I am unclear
>> what those coeficients are applied to.With spline I understand the
>> "noraml" coefficients applied to a cubic polynomial. But these
>> coefficients I am not sure how to interpret. If I had a description
>> of the algorithm maybe I could figure it out but as it is I have this
>> question. Any help?
>>
>> Kevin
>>
>> ______________________________________________
>> 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.
>>
>



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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. Received on Fri 18 Jul 2008 - 15:34:36 GMT

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