variogram problem
This is the the data set and want to make variogram for Cd15. The distance between each sample location was 4 cross 4 km. Please suggest me how to allocate initial guess about nugget, sill and range parametrs. Moreover, I have used log transformation for my variable Cd15. Is it appropriate? Or there is any other transformation for this. Thanks, Regards Adeela On Wed, Jun 24, 2015 at 7:08 PM, Edzer Pebesma <
edzer.pebesma at uni-muenster.de> wrote:
Thierry is right about that; without that we can only guess, which is what I will do now. fit.variogram does a non-linear fit using some steepest descent method, and needs initial values for that. The initial values you provide are 1 (partial sill), 5 (range), and 1 (nugget). In case v does not provide good information on how to improve these initial values, e.g. because 5 is smaller than the smallest distance in it, it can't figure out where to go in order to improve. This means it got stuck, and gives this warning. The plot plot(v, vgm(1, "Sph", 5, 1)) will reveal the problem to you (and to us, if you'd share it). On 06/24/2015 03:42 PM, Thierry Onkelinx wrote:
You'll need to provide a reproducible example. Your code is not reproducible without the data. ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek / Research Institute for Nature
and
Forest team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance Kliniekstraat 25 1070 Anderlecht Belgium To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to
say
what the experiment died of. ~ Sir Ronald Aylmer Fisher The plural of anecdote is not data. ~ Roger Brinner The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of
data.
~ John Tukey 2015-06-24 15:23 GMT+02:00 adeela uaf <adeela.uaf at gmail.com>:
Hi, Can anybody help me in fitting variogram in gstat package in R. I am
trying
but having this problem. Where Cd15 is the amount of Cadmium in soil at
15
cm depth.
v<-variogram(Cd15~1,data)
v.fit<-fit.variogram(v,vgm(1,"Sph",5,1))
Warning message:
In fit.variogram(v, vgm(1, "Sph", 5, 1)) :
Warning: singular model in variogram fit
******************************
Adeela
University of Agriculture Faisalabad
Department of Math & Stat.
[[alternative HTML version deleted]]
_______________________________________________ R-sig-Geo mailing list R-sig-Geo at r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo
[[alternative HTML version deleted]]
_______________________________________________ R-sig-Geo mailing list R-sig-Geo at r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo
-- Edzer Pebesma Institute for Geoinformatics (ifgi), University of M?nster, Heisenbergstra?e 2, 48149 M?nster, Germany; +49 251 83 33081 Journal of Statistical Software: http://www.jstatsoft.org/ Computers & Geosciences: http://elsevier.com/locate/cageo/ Spatial Statistics Society http://www.spatialstatistics.info
_______________________________________________ R-sig-Geo mailing list R-sig-Geo at r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo
-------------- next part -------------- An HTML attachment was scrubbed... URL: <https://stat.ethz.ch/pipermail/r-sig-geo/attachments/20150624/4962f3a6/attachment.html> -------------- next part -------------- A non-text attachment was scrubbed... Name: lyallpur.csv Type: text/csv Size: 2526 bytes Desc: not available URL: <https://stat.ethz.ch/pipermail/r-sig-geo/attachments/20150624/4962f3a6/attachment.bin>