Different variogram fitting results from gstat in R than from standalone gstat
Luka, this is hard to tell from here. The first thing I would try to find out is whether the sample variograms from both approaches are _exactly_ the same or not. For one thing, the X=x&y&xy in gstat stand-alone does standardize coordinates, the formula approach in R/gstat does not. Maybe follow-up on the gstat-info list? -- Edzer
Luka Honzak wrote:
Hi everyone,
I am trying to move my work from standalone gstat to R and I found
that variogram fitting gives different results in R than in standalone
gstat, while variograms are the same.
I want to know if I have done something wrong in R and what.
*gstat:
-set fit = 7; 6.56882 Nug(0) + 584.336 Sph(27110.8)
-set fit = 1; 156.687 Nug(0) + 444.965 Sph(35817.8)
*R:
-fit.method=7
model psill range
1 Nug 3.027124 0.00
2 Sph 593.518692 27282.76
-fit.method=1
model psill range
1 Nug 287.9900 0.00
2 Sph 354.8136 55421.58
*gstat commandline file:
data(RR): 'gstat_2000_5_NV.txt', x=1, y=2, v=4, X=x&y&xy;
variogram(RR): 70 Nug(0) + 600 Sph(30000);
set fit = 7;
set cutoff = 150000;
set width = 6000;
*R code:
library(gstat)
table=read.table("gstat_2000_5_NV.txt")
colnames(table)<-c("x","y","z","RR")
g <- gstat(id = "test", formula = RR~x+y+x*y, locations = ~x+y, data = table)
m <- vgm(600, "Sph", 30000, 70)
v.fit <- fit.variogram(variogram(g), m, fit.method=7)
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Edzer Pebesma Institute for Geoinformatics (ifgi), University of M?nster Weseler Stra?e 253, 48151 M?nster, Germany. Phone: +49 251 8333081, Fax: +49 251 8339763 http://ifgi.uni-muenster.de/ http://www.springer.com/978-0-387-78170-9 e.pebesma at wwu.de