[R-sig-Geo] Universal Kriging with factor covariate

[piero campa]

Ok sure.
I will hereby simulate the interpolation of a target variable "points"
(whose data is attached) via a single factor predictor "classes" created
randomly over the region of interest:

# libraries
library(sp)
library(gstat)
library(automap)

# Import the point pattern from the txt file and turn it to Spatial
# (set properly the path variable)
points <- read.table(path, header=TRUE)
coordinates(points)<- ~ LON+LAT

# Create grid enclosing the points and fill it with random factor data 
grid <- GridTopology(c(9,43.5), c(.1,.1), c(40, 20))
SPgrid <- SpatialGridDataFrame(grid, data.frame(classes=round(runif(40*20,
1, 10))))
SPgrid$classes <- as.factor(SPgrid$classes)

# Overlay the factor covariate onto the points
ov <- overlay(SPgrid, points)
points$CL <- ov$classes

# Create the linear regression model
lm <- lm(pm10 ~ CL, points)
summary(lm)

# Fit the variogram of the residuals
rvar <- autofitVariogram(residuals(lm) ~ 1, points)

# Regression Kriging
pm10.rk <- krige(lm$call$formula, points, SPgrid, rvar)
--> HERE I HAVE ERROR:
Error in function (classes, fdef, mtable)  : 
  unable to find an inherited method for function "krige", for signature
"call", "SpatialPointsDataFrame"

Hope this helps getting closer to the problem,
Piero

http://r-sig-geo.2731867.n2.nabble.com/file/n6011444/2009-045.ARPA.txt
2009-045.ARPA.txt 
-- 
View this message in context: http://r-sig-geo.2731867.n2.nabble.com/Universal-Kriging-with-factor-covariate-tp6009230p6011444.html
Sent from the R-sig-geo mailing list archive at Nabble.com.