# [R] Derivation of data points

jessica.gervais at tudor.lu jessica.gervais at tudor.lu
Wed Jan 16 11:35:15 CET 2008

```Dear All,

I would like to make the derivation of a points.
I tried to use D1tr (linear interpolation).
I also tried to used D1ss (spline interpolation) but I do not realy know
how to choose the smothing parameter the best.
D1ss(x, y, xout = x, spar.offset = 0.1384, spl.spar=NULL)

Here is an example of data I would like to derive

library(sfsmisc)
x<-c(30:90)
y<-c(39.10111,39.71601,40.4367,41.11309,42.02203,42.96469,43.88154,44.72341,45.50918,46.29508,47.29949,48.30178,49.00582,49.7295,50.50255,51.24946,51.8912,52.49289,53.11462,53.61668,54.11853,54.61826,55.16866,55.70223,56.32028,57.10335,57.95425,58.9606,60.68077,61.2205,61.7642,62.51613,63.10644,64.12183,64.67105,66.62656,67.19005,68.16018,69.29873,69.64272,70.20944,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA)

D1tr()
D1ss(x, y, xout = x, spar.offset = 0.1384, spl.spar=NULL)

D1ss(x, y, xout = x, spar.offset = 0.1384, spl.spar=NULL)
Error in smooth.spline(x, y) :
NA/NaN/Inf in foreign function call (arg 4)

Is there a way to return NA for points where there is an NA value as input
?

Could anyone give me some advices how to choose values for these
"spar.offset" and "spl.spar" parameters ?

Jessica

_________________________________________

Jessica Gervais
Tel: +352- 425991-628
Mail: jessica.gervais at tudor.lu

Resource Centre for Environmental Technologies,
Public Research Centre Henri Tudor,
Technoport Schlassgoart,
66 rue de Luxembourg,
P.O. BOX 144,
L-4002 Esch-sur-Alzette, Luxembourg

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