correlogram {bispdep} R Documentation

## Computes Moran's or Geary's coefficients on distance classes

### Description

Computes Moran's or Geary's coefficients on distance classes from a set of spatial coordinates and corresponding z values

### Usage

correlogram(coords, z, method="Moran", nbclass = NULL, zero.policy=NULL, ...)


### Arguments

 coords a two columns array, data.frame or matrix of spatial coordinates. Column 1 = X, Column 2 = Y. z a vector for the values at each location. Must have the same length as the row number of coords method the method used. Must be "Moran" (default) or "Geary" nbclass number of bins. If NULL Sturges method is used to compute an optimal number zero.policy default NULL, use global option value; if TRUE assign zero to the lagged value of zones without neighbours, if FALSE assign NA ... further arguments to pass to e.g. moran.test or geary.test

### Details

Uses the library spdep including moran.test or geary.test. Distances are euclidian and in the same unit as the spatial coordinates. Moran's Ho: I values larger than 0 due to chance; Geary's Ho: C values lesser than 1 due to chance. Correlog has print and plot methods; statistically significant values (p<0.05) are plotted in red.

### Value

An object of class "correlog", a matrix including:

 class bin centers I the coefficient values p.value probability of Ho n the number of pairs low.l bin lower limit up.l bin upper limit

### Warning

Computing can take a long time for large data sets

### References

see library spdep

### See Also

geary.test, moran.test

### Examples


library(spdep)
data(oldcol)
attach(COL.OLD)
coords<-cbind(X,Y)
corM <- correlogram(coords,CRIME,zero.policy=TRUE)
corM
plot(corM)

corG <- correlogram(coords,CRIME,method="Geary",zero.policy=TRUE)
corG
plot(corG)



[Package bispdep version 1.0-0 Index]