Dear all,
I read in ASDAR: "Residual variograms are calculated by default when a
more complex model for the trend is used..."
However, I noticed that when using fit.variogram in gstat with an
additional option: degree=2, but keeping the formula as an intercept
only, does not account for the higher degree of complexity in the
model. I suspect this is not the intended behavior. To honour a
dependence structure (polyn degree) in my observations I need to state
the dependence explicitly in the formula.
Best regards,
Caspar
data(meuse)
coordinates(meuse) <- c("x", "y")
v<-variogram(log(zinc)~1,meuse)
print(v)
vs<-variogram(log(zinc)~1,meuse,degree=2)
print(vs)
vt<-variogram(log(zinc)~x*y+I(x^2)+I(y^2),meuse)
print(vt)
PS:
x86_64-w64-mingw32/x64 (64-bit)
R version 3.0.1 (2013-05-16)
gstat_1.0-16
Note on variogram fitting with polynomial degree
3 messages · Caspar Hallmann, Edzer Pebesma
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 degree is not listed as a parameter in ?variogram, and is ignored, regrettably silently, but this is how R often works when there's a ... in the argument list. The function that accepts degree is ?gstat, and I tried: variogram(gstat(NULL, "lzinc", log(zinc)~1, meuse, degree=2)) and that gives a nice error message that degree is not supported by variogram(). I understand this is somewhat confusing. Do you think we should modify the book or the documentation of some function?
On 09/17/2013 11:36 AM, Caspar Hallmann wrote:
Dear all,
I read in ASDAR: "Residual variograms are calculated by default
when a more complex model for the trend is used..."
However, I noticed that when using fit.variogram in gstat with an
additional option: degree=2, but keeping the formula as an
intercept only, does not account for the higher degree of
complexity in the model. I suspect this is not the intended
behavior. To honour a dependence structure (polyn degree) in my
observations I need to state the dependence explicitly in the
formula.
Best regards,
Caspar
data(meuse) coordinates(meuse) <- c("x", "y")
v<-variogram(log(zinc)~1,meuse) print(v)
vs<-variogram(log(zinc)~1,meuse,degree=2) print(vs)
vt<-variogram(log(zinc)~x*y+I(x^2)+I(y^2),meuse) print(vt)
PS: x86_64-w64-mingw32/x64 (64-bit) R version 3.0.1 (2013-05-16)
gstat_1.0-16
_______________________________________________ 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. Phone: +49 251 83 33081, Fax: +49 251 8339763 http://ifgi.uni-muenster.de -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBAgAGBQJSOC6KAAoJEM1OCHCtOnfx6dkH/iIluvBI83ghDMoNIb+/rTDz LOtVwu8oZp90vGIAVltBbqPVIu4SZH4jj6jif0HrEJU3wshE4k51EkGwq77jvP13 +pnCrwApeBHpJ2iUgYgqYCJAkwj+F25HxX1IxjcmQVIe8LC6O3fl/Rr8WAdnqbAL M3J8nzEf23yWba683BCBxQwDBHbaTSHYlrKjAbEyQWsnVY40lBV0Vl7SdooseyWK jPdEFPhp3kQIpPKhbmoAo9PwocwfUympZZ0KbM3xosZrI2cfI1dXXzrOwJtsCBrW 7/pK9fOxDYfGZICEnSr3xkf3FQCaoFQZY5uVEIrOo67/GkNxt5ewBkIdsQCi+vc= =m5bR -----END PGP SIGNATURE-----
Hi Edzer, Thanks for the clarification. Well, ideally, I think variogram() should be made possible to account for "degree". Alternatively a simple note in the help file for variogram along the lines "NOTE: degree is not used in variogram(), Use formula to specify a trend surface instead", might suffice. Thanks again Caspar On Tue, Sep 17, 2013 at 12:27 PM, Edzer Pebesma
<edzer.pebesma at uni-muenster.de> wrote:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 degree is not listed as a parameter in ?variogram, and is ignored, regrettably silently, but this is how R often works when there's a ... in the argument list. The function that accepts degree is ?gstat, and I tried: variogram(gstat(NULL, "lzinc", log(zinc)~1, meuse, degree=2)) and that gives a nice error message that degree is not supported by variogram(). I understand this is somewhat confusing. Do you think we should modify the book or the documentation of some function? On 09/17/2013 11:36 AM, Caspar Hallmann wrote:
Dear all,
I read in ASDAR: "Residual variograms are calculated by default
when a more complex model for the trend is used..."
However, I noticed that when using fit.variogram in gstat with an
additional option: degree=2, but keeping the formula as an
intercept only, does not account for the higher degree of
complexity in the model. I suspect this is not the intended
behavior. To honour a dependence structure (polyn degree) in my
observations I need to state the dependence explicitly in the
formula.
Best regards,
Caspar
data(meuse) coordinates(meuse) <- c("x", "y")
v<-variogram(log(zinc)~1,meuse) print(v)
vs<-variogram(log(zinc)~1,meuse,degree=2) print(vs)
vt<-variogram(log(zinc)~x*y+I(x^2)+I(y^2),meuse) print(vt)
PS: x86_64-w64-mingw32/x64 (64-bit) R version 3.0.1 (2013-05-16)
gstat_1.0-16
_______________________________________________ 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. Phone: +49 251 83 33081, Fax: +49 251 8339763 http://ifgi.uni-muenster.de -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBAgAGBQJSOC6KAAoJEM1OCHCtOnfx6dkH/iIluvBI83ghDMoNIb+/rTDz LOtVwu8oZp90vGIAVltBbqPVIu4SZH4jj6jif0HrEJU3wshE4k51EkGwq77jvP13 +pnCrwApeBHpJ2iUgYgqYCJAkwj+F25HxX1IxjcmQVIe8LC6O3fl/Rr8WAdnqbAL M3J8nzEf23yWba683BCBxQwDBHbaTSHYlrKjAbEyQWsnVY40lBV0Vl7SdooseyWK jPdEFPhp3kQIpPKhbmoAo9PwocwfUympZZ0KbM3xosZrI2cfI1dXXzrOwJtsCBrW 7/pK9fOxDYfGZICEnSr3xkf3FQCaoFQZY5uVEIrOo67/GkNxt5ewBkIdsQCi+vc= =m5bR -----END PGP SIGNATURE-----
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