[R-sig-Geo] Warning in fit.variogram: value out of range in 'bessel k' | automap and gstat packages

[Frederico Faleiro]

Hi Jon and others,

thank you for your help. The problem is really in the Ste model (Matern, M.
Stein's parameterization). The warning only happens
when I execute this model. However in the gstat with the same parameters
for lambda have problem of convergency. Do you think the gstat have
different bevavior to the same issue?

av <- autofitVariogram(jan~1, pr, model = "Ste", verbose = T)
# In fit.variogram(experimental_variogram, model = vgm(psill = psill,  ...
:  value out of range in 'bessel_k'

# define the same kappa values of automap
seq.k <- c(0.05, seq(0.2, 2, 0.1), 5, 10)
ve <- variogram(jan~1, pr)
v <- fit.variogram(v, vgm("Ste"), fit.kappa = seq.k)
Warning messages:
1: In fit.variogram(object, model, fit.sills = fit.sills, fit.ranges =
fit.ranges,  :
  No convergence after 200 iterations: try different initial values?
2: In fit.variogram(object, model, fit.sills = fit.sills, fit.ranges =
fit.ranges,  :
  No convergence after 200 iterations: try different initial values?
3: In fit.variogram(o, m, fit.kappa = FALSE, fit.method = fit.method,  :
  No convergence after 200 iterations: try different initial values?


Best regards,

Frederico

On Wed, Sep 11, 2019 at 7:02 AM <Jon.SKOIEN using ec.europa.eu> wrote:

>
> Frederico,
>
>
> I don't think you need to worry about this warning in this case.
> autofitVariogram tests a lot of variogram models (and different
> kappa-values) in the search for the best one, and then fit.variogram tries
> to optimize the parameters based on these. It seems the warnings were
> generated in the C-code of gstat, based on some of the tested kappa-values
> for the Matern variogram (Stein implementation). It also seems that these
> kappa values did not give good fits to the sample variogram, so you did not
> get the warning from the best fit variogram in this case.
>
>
> Hope this helps,
>
> Jon
>
>
>
> --
> Jon Olav Skøien
> European Commission
> Joint Research Centre – JRC.E.1
> Disaster Risk Management Unit
> Building 26b 1/144 | Via E.Fermi 2749, I-21027 Ispra (VA) Italy, TP 267
> jon.skoien using ec.europa.eu <https://remi.webmail.ec.europa.eu/owa/redir.aspx?C=O12RUARdbvGA3WF3zGoSV0j5xMoZlQcIEwiS4Y9G8jzXRqCCC1HUCA..&URL=mailto%3ajon.skoien%40jrc.ec.europa.eu> Tel:  +39 0332 789205 Disclaimer: Views expressed in this email are those of the individual and do not necessarily represent official views of the European Commission.
>
>
> ------------------------------
> *From:* R-sig-Geo <r-sig-geo-bounces using r-project.org> on behalf of
> Frederico Faleiro <fvfaleiro using gmail.com>
> *Sent:* 09 September 2019 21:28:32
> *To:* RsigGeo
> *Subject:* [R-sig-Geo] Warning in fit.variogram: value out of range in
> 'bessel k' | automap and gstat packages
>
> Dear list,
>
> I am trying make an interpolation with the function autoKrige from the
> package automap, but I received more than 50 times the following warning
> message:
>
> In fit.variogram(experimental variogram, model = vgm(psill = psill, ... :
> value out of range in 'bessel k'
>
> I have tryed identify it in the code of fit.variogram and vgm from the
> gstat package, but they do not have any warning about it in the code. Then
> I imagine the warning is from another function.
> I fitted the variogram automatically in the automap and after I fitted in
> the gstat to check if there is the same warning for that parameters, but in
> the last I do not have any warning. When I check the variogram model, it
> has a good fit apparently. I provided the reproductible example below.
>
> Do you know the consequences of this warning and how can I avoid it? I
> would like to use the automap package because I need interpolate many other
> files like this.
>
> # example
> library(automap)
> library(sp)
>
> # download the data in:
>
> https://urldefense.proofpoint.com/v2/url?u=https-3A__drive.google.com_file_d_1L33-5FQgpNMdwvWff-5FuMrwhl-5FKCajrtlVe_view-3Fusp-3Dsharing&d=DwICAg&c=8NwulVB6ucrjuSGiwL_ckQ&r=DA6jV5X00Z1YpyMh4OS79xeSQGErBqY83CBz841DNnU&m=YlpT3yKlbNVLvXMp08O8X1LkniHGXTzJeLDHLTotwOI&s=U2z98vHb1mpKhKJ9UXA0RUrPi6r6IXibq1cuuyB0jWY&e=
> # read the data
> pr <- read.table('pr_monC.txt', header = TRUE, sep = "\t")
> coordinates(pr) <- ~long+lat
> # read the grid
> gr <- read.table('grid.txt' , header = TRUE, sep = '\t')
> gridded(gr) <-  ~long+lat
>
> # automatic fit variogram with automap
> av <- autofitVariogram(jan~1, pr)
> # warnings message:   In fit.variogram(experimental variogram, model =
> vgm(psill = psill, ... : value out of range in 'bessel k'
> plot(av) # get in the graph the parameters to fit the variogram
>
> # fit variogram in gstat with the model parameters from autofitVariogram to
> check if there is any warning message too
> ve <- variogram(jan~1, pr)
> v <- fit.variogram(ve, vgm(psill = 9723, model = "Ste", range = 20, nugget
> = 194, kappa = 0.8))
> # it does not produce any warning
> plot(ve, v)
>
> Best regards,
>
> Frederico
>
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