Indicator Simulation Help
Hi There, I am trying to do conditional indicator simulation on some TCE values in groundwater. I set my data up as a SpatialPointsDataFrame and expanded a grid to predict to that is a SpatialPixelsDataFrame.
From there, here is my code:
for(i in 1:length(data$TCE_.mg.L.)) (if(data$TCE_.mg.L.[i]<=0.005) data$TCE_.mg.L.ind[i] = 1 else data$TCE_.mg.L.ind[i] = 0) #Compute and plot the sample variogram for the indicator transform TCE.var<-variogram(TCE_.mg.L.ind~1, data) plot(TCE.var) #Set initial choice of variogram model # calculate variance as estimate of the sill var(data$TCE_.mg.L.ind) # [1] 0.2491694 TCE.vgm<-vgm(.25, "Sph", 40) TCE.model<-fit.variogram(TCE.var, TCE.vgm) TCE.model # model psill range #1 Sph 0.2770698 50.82271 # try gstat and predict.gstat for simulation g <- gstat(id = "TCE_.mg.L.ind", formula = TCE_.mg.L.ind~1,data = data,model=TCE.model) class(g) #[1] "gstat" "list" TCE.sim<-predict.gstat(g, site1.grid,nsim=1,indicators=TRUE) summary(TCE.sim) #Object of class SpatialPixelsDataFrame #Coordinates: # min max #x 90 110 #y 75 85 #Is projected: NA #proj4string : [NA] #Number of points: 231 #Grid attributes: # cellcentre.offset cellsize cells.dim #x 90 1 21 #y 75 1 11 #Data attributes: # Min. 1st Qu. Median Mean 3rd Qu. Max. #0.00000 0.00000 0.00000 0.09524 0.00000 1.00000 My issue is how to get the simulated values for each pixel. I tried TCE.sim[1] and I just get a list of the coordinates in X and Y. I also need to extract the value of the mean. Also, the output seems off to me, does this look typical of indicator simulation? If I plot with spplot(TCE.sim[1]) I get a plot with just zeros and 1s. From my understanding, indicator simulation gives values between 0-1. Any advice is appreciated! Thank you! Katie -- Katherine Lockhart Graduate Student Researcher UC Davis Department of Land, Air, and Water Resources