Function to compute Moran's index of spatial autocorrelation

This function computes Moran's I statistic and provide a testing procedure using random permutations. It is based on the moran.mc function of the spdep package. The moran.randtest is slightly different as it allows to consider several variables (x can have more than one columns) and its ouputs are objects of class randtest (one variable) or krandtest (several variables).

moran.randtest(x, listw, nrepet = 999, ...)

Arguments

x: a vector, matrix or data.frame with numeric data
listw: an object of class listw created for example by nb2listw
nrepet: an integer indicating the number of permutations used in the randomization procedure
...: other arguments to be passed to the as.randtest or as.krandtest functions.

Value

An object of class randtest (one variable) or krandtest (several variables)

References

Moran, P. A. P. (1950). Notes on continuous stochastic phenomena. Biometrika, 37, 17-23.

Author

Stéphane Dray stephane.dray@univ-lyon1.fr

Examples


if(require("ade4", quietly = TRUE)  & require("spdep", quiet = TRUE)){
data(mafragh)
tests <- moran.randtest(mafragh$env, nb2listw(mafragh$nb))
tests
plot(tests)

}