creating a variogram with gstat in R

[femke]

Hello again,   Sorry to be dense about this but I'm still having trouble working out how gstat operates within R in terms of data import (the data import phase isn't in the examples in the demos).   I import my data fine - and have been trying it with two approaches, one with the original ascii grid (dataA) and the other with a csv list of x,y, and value (dataB).   > dataA <- read.table(file="testData.txt", sep=" ", na.strings = "-9999", skip = 6) > dataB <- read.table("testData2.csv", sep=",", header=TRUE,  row.names=1)   In attempting to plot a basic variogram, I do the following and get the an error message I can't interpret (nor is there much help on line with this error message):   > v <- variogram(log(A1)~1,loc= ~x+y, dataB) Error in vector("double", length) : negative length vectors are not allowed I'm also wondering how the variogram function knows which column is x and which y (as is specified in the command files), or is the x and y coded in?   With dataA (the asciigrid) I'm not even sure how to create a variogram as it doesn't have a column header.   Please help.   Thanks in advance, and apologies for the simplistic questions.   femke