1. the "grid" argument can also taka a matrix with coordinates values.

2. grf produces "uncoditional" simulations.

P.J.

> Hello,

>

> My name is Matthew Sokol and I am writing this list serve to ask some

> help. Currently I am a master's student at the University of Nevada

> and have come across a problem using R that I can not solve.

>

> Here is my problem:

> I am using the R package geoR, specifically the function grf to simulate data.

>

> Basically I have a data set that contains an Easting and Northing

> coordinate system and a Z value. From this system I wish to perform

> Ordinary Kriging. So I run the following command lines in R:

> > dat<-read.table("examplepb.dat",header=TRUE)

> > geodat<-as.geodata(dat)

> > plot(geodat)

> > vario<-variog(geodat)

> > lines.variomodel(cov.model="gaussian",nugget=1800,cov.pars=c(1400,60),max.dist=150)

>

> Now since I know the Nugget, Sill, and Range for the variogram model,

> I wish to simulate more data that follows the same variogram model. So

> I run the following command line:

>

> > simdat<-grf(625,grid="reg",nugget=1800,cov.pars=c(1400,60))

>

> Now, the problem with this command is that it produces data on grid

> that is 1 x 1 (all the Northing and easting coordinates are now a

> number 0-1). But my easting and northing coordinates have the

> following properties:

>

> Easting: Min 254.4 Max: 492

> Northing: Min 118 Max 315

>

> Which is not a 1 x 1 grid.

>

> I know my problem is in this statement: grid="reg"

> I tried the following commands:

> Loci<-expand.grid(seq(250,500,l=250),seq(115,320,l=205))

> So now I run:

> > simdat<-grf(625,grid=loci,nugget=1800,cov.pars=c(1400,60))

>

> Which produces so much data that I can not R console will not display it.

>

> So I run the following R commands:

> geosim<-as.geodata(simdat)

> > variosim<-variog(geosim)

> variog: computing omnidirectional variogram

> Error in vector("double", length) : cannot allocate vector of length 1444504375

>

> So now I get an error. I think i may be producing to much data with my

> simulation?

>

> I am lost. I've looked through the manuals but have not found much on

> conditional simulation. I was wondering if anyone knew of a problem

> like this or where I can look to find more information.

>

> I am sorry if the question is trivial as I have been reading the posts

> on this list serve and everyone here has a command of the language far

> surpass mine. Thank you for your time.

>

>

> -Matthew Sokol

>

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>