problems in anisotropy detection

classic Classic list List threaded Threaded
2 messages Options
Reply | Threaded
Open this post in threaded view
|

problems in anisotropy detection

Emanuele Barca
Dear friends,

I have a dataset of hydraulic heads, mydata = <X, Y, HH, Z> and i would
like to check for anisotropy.

In R I found 3 functions to carry out such task:

1. likfit

x_geodata <- as.geodata(mydata, coord.cols = 1:2, data.col = 3,
                         covar.col = 4)
fit_mle  <- likfit(x_geodata,
                    fix.nugget = FALSE,
                    cov.model = "exponential", psiA = 0, psiR = 1,
                    ini = c(var(Y), 1), fix.psiA = FALSE, fix.psiR =
FALSE,
                    hessian = TRUE)

that detects no anisotropy.

2. estimateAnisotropy

mydata.sp <- mydata
coordinates(mydata.sp) = ~ X + Y
estimateAnisotropy(mydata.sp, depVar = "LivStat", "LivStat ~ Z")

that returns the following

[generalized least squares trend estimation]
$`ratio`
[1] 1.340775

$direction
[1] -35.29765

$Q
               Q11          Q22          Q12
[1,] 1.926136e-05 2.329241e-05 5.721893e-06

$doRotation
[1] TRUE

finally,

3. estiStAni

vmod1 <- fit.variogram(vgm1, vgm(18, "Ste", 1300, 0.78, kappa = 1.7))
estiStAni(vgm1, c(10, 150), "vgm", vmod1)

that returns an error:

Error in `$<-.data.frame`(`*tmp*`, "dir.hor", value = 0) :
   replacement has 1 row, data has 0.

I am very puzzled, can anyone help me understanding if there is
anisotropy in my dataset?

thanks

emanuele

_______________________________________________
R-sig-Geo mailing list
[hidden email]
https://stat.ethz.ch/mailman/listinfo/r-sig-geo
Reply | Threaded
Open this post in threaded view
|

Re: problems in anisotropy detection

Sebastiano Trevisani
Dear Emanuele,

Did you first checked manually the presence of anisotropy with gstat
variogram function? Then consider also that automatic fitting procedure
generally are not capable to fit a zonal anisotropy but only a geometric
one.

Sebastiano


Il sab 13 lug 2019, 07:32 Emanuele Barca <[hidden email]> ha
scritto:

> Dear friends,
>
> I have a dataset of hydraulic heads, mydata = <X, Y, HH, Z> and i would
> like to check for anisotropy.
>
> In R I found 3 functions to carry out such task:
>
> 1. likfit
>
> x_geodata <- as.geodata(mydata, coord.cols = 1:2, data.col = 3,
>                          covar.col = 4)
> fit_mle  <- likfit(x_geodata,
>                     fix.nugget = FALSE,
>                     cov.model = "exponential", psiA = 0, psiR = 1,
>                     ini = c(var(Y), 1), fix.psiA = FALSE, fix.psiR =
> FALSE,
>                     hessian = TRUE)
>
> that detects no anisotropy.
>
> 2. estimateAnisotropy
>
> mydata.sp <- mydata
> coordinates(mydata.sp) = ~ X + Y
> estimateAnisotropy(mydata.sp, depVar = "LivStat", "LivStat ~ Z")
>
> that returns the following
>
> [generalized least squares trend estimation]
> $`ratio`
> [1] 1.340775
>
> $direction
> [1] -35.29765
>
> $Q
>                Q11          Q22          Q12
> [1,] 1.926136e-05 2.329241e-05 5.721893e-06
>
> $doRotation
> [1] TRUE
>
> finally,
>
> 3. estiStAni
>
> vmod1 <- fit.variogram(vgm1, vgm(18, "Ste", 1300, 0.78, kappa = 1.7))
> estiStAni(vgm1, c(10, 150), "vgm", vmod1)
>
> that returns an error:
>
> Error in `$<-.data.frame`(`*tmp*`, "dir.hor", value = 0) :
>    replacement has 1 row, data has 0.
>
> I am very puzzled, can anyone help me understanding if there is
> anisotropy in my dataset?
>
> thanks
>
> emanuele
>
> _______________________________________________
> R-sig-Geo mailing list
> [hidden email]
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>

        [[alternative HTML version deleted]]

_______________________________________________
R-sig-Geo mailing list
[hidden email]
https://stat.ethz.ch/mailman/listinfo/r-sig-geo