Have you seen an example on how to do it in R? I found no practical examples...
On 2/27/06, vito muggeo <[EMAIL PROTECTED]> wrote: > > Dear Micheal, > > > the output of the "ns" function in R is "basis matrix", but then > Yes you are right, the output of the ns(x, df) is the basis matrix of a > natural cubic spline with df degrees of freedom. See ?ns (in package > splines) on how to specify df or knots or .. > > Fitting y~ns(x,df) yields a smooth curve given by a linear combination > of the basis functions (the single colums of the basis matrix) by the > estimated coefficients (returned by the fitted model). > > As far as I know, a tensor product is usually employed to > multidimensional smoothing and the multidimensional basis is formed via > the kronecker product of the marginal bases. > > Finally, last but not least: Probably you need some statistical > backaground on spline fitting.. > Please, read some statistical papers/books on such topic (for instance > see references in packages splines, mgcv) > > best, > vito > > Michael wrote: > > Hi all, > > > > Could anybody recommend some easy-to-understand and example based > > notes/tutorials on how to use cubic splines to do filtering on > > multi-dimension data? > > > > I am confused by the 1-dimensional case, and more confused by > > multi-dimensional case. > > > > I found all the books suddenly become very abstract when it comes to > this > > subject. > > > > They don't provide examples in R or Splus at all. > > > > Specifically, I don't know how to provide data "x" to the "ns" function > in > > R, > > > > and I don't understand what should be the output matrix, and how to use > the > > output matrix to "filter" data? > > > > Books mention about basis matrix, design matrix, model matrix, data > matrix, > > etc. I got lost. > > > > I presume the output of the "ns" function in R is "basis matrix", but > then > > how do I use it? How to form tensor-product? > > > > I don't understand it at all. > > > > Please help me! > > > > Thank you very much! > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@stat.math.ethz.ch mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > > > -- > ==================================== > Vito M.R. Muggeo > Dip.to Sc Statist e Matem `Vianelli' > Università di Palermo > viale delle Scienze, edificio 13 > 90128 Palermo - ITALY > tel: 091 6626240 > fax: 091 485726/485612 > ==================================== > [[alternative HTML version deleted]]
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