Hallo Duncan Thanks, I was not aware of this package. I will try.
Petr > -----Original Message----- > From: Duncan Murdoch <murdoch.dun...@gmail.com> > Sent: Thursday, January 26, 2023 3:44 PM > To: PIKAL Petr <petr.pi...@precheza.cz>; r-help@r-project.org > Subject: Re: [R] akima interp results to zero with less than 10 values > > The akima package has a problematic license (it doesn't allow commercial > use), > so it's been recommended that people use the interp package instead. When I > use interp::interp instead of akima::interp, I get reasonable output from > your > example. > > So that's another reason to drop akima... > > Duncan Murdoch > > On 26/01/2023 9:35 a.m., PIKAL Petr wrote: > > Dear all > > > > I have this table > >> dput(mat) > > mat <- structure(c(2, 16, 9, 2, 16, 1, 1, 4, 7, 7, 44.52, 42.8, 43.54, > > 40.26, 40.09), dim = c(5L, 3L)) > > > > And I want to calculate result for contour or image plots as I did few > > years ago. > > > > However interp does not compute the z values and gives me zeros in z > > matrix. > > library(akima) > > > >> interp(mat[,1], mat[,2], mat[, 3], nx=5, ny=5) > > $x > > [1] 2.0 5.5 9.0 12.5 16.0 > > > > $y > > [1] 1.0 2.5 4.0 5.5 7.0 > > > > $z > > [,1] [,2] [,3] [,4] [,5] > > [1,] 0 0 0 0 0 > > [2,] 0 0 0 0 0 > > [3,] 0 0 0 0 0 > > [4,] 0 0 0 0 0 > > [5,] 0 0 0 0 0 > > > > With the example from help page if less than 10 values are used, the > > result is also zero interp(akima$x[1:9], akima$y[1:9], akima$z[1:9], > > nx=5, ny=5) > > > > but with 10 or more values the result is correctly calculated > > interp(akima$x[1:10], akima$y[1:10], akima$z[1:10], nx=5, ny=5) $x [1] > > 0.0000 6.1625 12.3250 18.4875 24.6500 > > > > $y > > [1] 1.24 5.93 10.62 15.31 20.00 > > > > $z > > [,1] [,2] [,3] [,4] [,5] > > [1,] NA NA NA NA 34.60000 > > [2,] NA NA 27.29139 27.11807 26.60971 > > [3,] NA 19.81371 19.63614 19.12778 18.61943 > > [4,] NA 14.01443 10.66531 11.13750 10.62914 > > [5,] NA NA NA NA NA > > > > Help page says > > x, y, and z must be the same length (execpt if x is a > > SpatialPointsDataFrame) and may contain no fewer than ***four*** points. > > > > So my understanding was that 5 poins could be used but I am obviously > wrong. > > Is it a bug in interp or in the documentation or is it my poor > > understanding of the whole matter. > > > > Best regards > > Petr > > > > > > ______________________________________________ > > 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.
______________________________________________ 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.
