Just a note: There is no such thing as "a best fitting curve" that must pass through all the points.
You may wish to consult a statistician or spend time with references to clarify your intent. Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Wed, Jan 22, 2020 at 7:01 AM Tung Nguyen <thanhtungmi...@gmail.com> wrote: > Hello R-Help, > > I'm trying to find the best fitting curve through a given set of points. > The fitted curve must also pass through these points. I found an answer on > Cross Validated which suggested to use the `cobs: Constrained B-Splines > (Sparse Matrix Based)` package. However, I got an error while testing it > with my sample data: > > Error in x %*% coefficients: NA/NaN/Inf in foreign function call (arg 2) > > *My question*: what caused this error and how can I fix it? Any suggestion > is greatly appreciated. Thanks! > > library(cobs) > > dat <- data.frame( > x = c(1e-06,0.25,0.5,0.75,1,2,3,4,5,6), > y = c(1e-07,1.925,2.9625,3.469375, > 3.875,4.5315,4.89,5.09375,5.216,5.46)) > dat > #> x y#> 1 1.0e-06 0.0000001#> 2 2.5e-01 > 1.9250000#> 3 5.0e-01 2.9625000#> 4 7.5e-01 3.4693750#> 5 1.0e+00 > 3.8750000#> 6 2.0e+00 4.5315000#> 7 3.0e+00 4.8900000#> 8 4.0e+00 > 5.0937500#> 9 5.0e+00 5.2160000#> 10 6.0e+00 5.4600000 > # visual inspection > plot(dat); lines(dat) > > # define constrained points > con <- matrix( > cbind(c(0,0,0,0,0,0,0,0,0,0), > c(1e-06,0.25,0.5,0.75,1,2,3, 4,5,6), > c(1e-07,1.925,2.9625,3.469375, > 3.875,4.5315,4.89,5.09375,5.216, 5.46)), > ncol = 3, nrow = 10) > # curve fitting > fit_result <- cobs(dat$x, dat$y, pointwise = con)*#> qbsks2(): > #> Performing general knot selection ... > #> Error in x %*% coefficients: NA/NaN/Inf in foreign function call (arg > 2)* > > > Best regards, > > -- Tung > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
