Re: [R] Error with constrained curve fitting through specific points

2020-01-23 Thread Tung Nguyen
Thanks Rui and everyone for your help! Using ` constraint = "increase"` and `lambda = 0.1` did it. If we ignore the first point, `lambda = -1` option is also possible. `cobs` will automatically choose a lambda value plot(fit_result) summary(fit_result) # COBS smoothing spl

Re: [R] Error with constrained curve fitting through specific points

2020-01-22 Thread Abby Spurdle
Sorry, I should have said "Spline Interpolation" (not spline fitting). __ 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-gui

Re: [R] Error with constrained curve fitting through specific points

2020-01-22 Thread Abby Spurdle
This is probably the *simplest* approach: > f = splinefun (dat$x, dat$y) > #simple plot > x = seq (0, 6,, 200) > plot (dat) > lines (x, f (x) ) If that's not what you want, perhaps you could expand on "constraints" or "best fitting"... Expanding on what Bert said, spline fitting and (regression

Re: [R] Error with constrained curve fitting through specific points

2020-01-22 Thread Rui Barradas
Hello, This seems to "work". It doesn't give errors nor warnings and the fitted line passes through the given points. fit_result <- cobs(dat$x, dat$y, constraint = "increase", lambda = 0.1, pointwise = con) plot(y~x, dat) pred <- predi

Re: [R] Error with constrained curve fitting through specific points

2020-01-22 Thread PIKAL Petr
Cheers Petr > -Original Message- > From: R-help On Behalf Of Tung Nguyen > Sent: Wednesday, January 22, 2020 4:01 PM > To: r-help@r-project.org > Subject: [R] Error with constrained curve fitting through specific points > > Hello R-Help, > > I'm trying to find t

Re: [R] Error with constrained curve fitting through specific points

2020-01-22 Thread Bert Gunter
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

[R] Error with constrained curve fitting through specific points

2020-01-22 Thread Tung Nguyen
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 te