units for spatial range in stvariogram gstat
Dear Prof. Pebesma, Thanks for reply I will try to make it more clear the coordinates are converted to decimal degree format using the equation DD = d + (min/60) + (sec/3600) and then projected using
llCRS <- CRS("+proj=longlat +ellps=WGS84")
pm10_sp <- SpatialPoints(coords, proj4string = llCRS)
pm10_sp
SpatialPoints:
longitude latitude
1 30.92500 29.95300
61 31.36000 30.26000
and the variogram is fitted using
varpm10 <- variogramST(lnpm10only~1,data=lnpm10_stfdf,cutoff=0.8,
assumeRegular=T,na.omit=T)
sumMetric <- vgmST("sumMetric", space = vgm(psill=5,"Mat", range=50,
nugget=0),time = vgm(psill=500,"Mat", range=50, nugget=0,kappa=0.3), joint = vgm(psill=10,"Mat", range=100, nugget=1), stAni=200)
sumMetric_Vgm <- fit.StVariogram(varpm10, sumMetric,
method="L-BFGS-B",lower=pars.l,upper=pars.u) *the s.range parameter extracted was 50.6 but if you take a look on the figure attached the largest distance on the x-axis is 0.6 ??????* *so i think the unit on the figure is not the unit of the extracted parameter. * by the way the largest ditance between any points in my data set is approximately 190 km Thanks again On Wed, May 17, 2017 at 10:08 PM, Edzer Pebesma <
edzer.pebesma at uni-muenster.de> wrote:
Your email is not nearly enough for a reader to figure out what you did. However, if your data are long/lat, and you instructed gstat about that (i.e., proj4string(pm10_sp) indicates coordinates are degrees) then gstat computes and returns distances in km. On 17/05/17 20:56, sara osama wrote:
Dear All, I have question concerning the unit of measurement for the range parameter in the fit.stvariogram in gstat, i have fitted the following spatio temporal variogram for data on monthly averages pf pm10 and the longitude and latitude are in decimel format
pm10_sp
SpatialPoints:
longitude latitude
1 30.92500 29.95300
61 31.36000 30.26000
121 31.33300 29.84720
and this is the commands for fitting the variogram
varpm10 <- variogramST(lnpm10only~1,data=lnpm10_stfdf,cutoff=0.8,
assumeRegular=T,na.omit=T)
plot(varpm10,map=F)
sumMetric <- vgmST("sumMetric", space = vgm(psill=5,"Mat", range=50,
nugget=0),time = vgm(psill=500,"Mat", range=50, nugget=0,kappa=0.3), joint = vgm(psill=10,"Mat", range=100, nugget=1), stAni=200)
sumMetric_Vgm <- fit.StVariogram(varpm10, sumMetric,
method="L-BFGS-B",lower=pars.l,upper=pars.u)
plot(varpm10,sumMetric_Vgm,map=F)
extractPar(sumMetric_Vgm)
sill.s range.s nugget.s sill.t range.t
nugget.t
1.73598444 50.63845035 0.03212857 0.01570379 49.99811448
0.00000000
sill.st <http://sill.st> range.st <http://range.st>
nugget.st <http://nugget.st> anis
0.00000000 100.00004052 0.09151787 200.00000000
--
now i want to know the units for these parameters in order to be able to
interpret it for example is it in km or m.
I really appreciate any help that I deeply need
Best Regards
Sara
Faculty of Economics & Political Science
Cairo University
Tel:(202)35728055-(202)35728116-(202)35736608-(202)35736605
Fax:(202)35711020
Follow us on twitter:https://twitter.com/fepsnews
_______________________________________________ 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/
_______________________________________________ R-sig-Geo mailing list R-sig-Geo at r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo
Best Regards Faculty of Economics & Political Science Cairo University Tel:(202)35728055-(202)35728116-(202)35736608-(202)35736605 Fax:(202)35711020 Follow us on twitter:https://twitter.com/fepsnews [[alternative HTML version deleted]]