spweights.constants {spdep}R Documentation

Provides constants for spatial weights matrices

Description

The function calculates the constants needed for tests of spatial autocorrelation for general weights matrices represented as listw objects. Note: from spdep 0.3-32, the values of S1 and S2 are returned correctly for both underlying symmetric and asymmetric neighbour lists, before 0.3-32, S1 and S2 were wrong for listw objects based on asymmetric neighbour lists, such as k-nearest neighbours (thanks to Luc Anselin for finding the bug).

Usage

spweights.constants(listw, zero.policy=FALSE, adjust.n=TRUE)
Szero(listw)

Arguments

listw a listw object from for example nb2listw
zero.policy if TRUE ignore zones without neighbours, if FALSE fail when encountered
adjust.n default TRUE, if FALSE the number of observations is not adjusted for no-neighbour observations, if TRUE, the number of observations is adjusted

Value

n number of zones
n1 n - 1
n2 n - 2
n3 n - 3
nn n * n
S0 global sum of weights
S1 S1 sum of weights
S2 S2 sum of weights

Author(s)

Roger Bivand Roger.Bivand@nhh.no

References

Haining, R. 1990 Spatial data analysis in the social and environmental sciences, Cambridge University Press, p. 233; Cliff, A. D., Ord, J. K. 1981 Spatial processes, Pion, p. 19, 21.

See Also

nb2listw

Examples

data(oldcol)
B <- spweights.constants(nb2listw(COL.nb, style="B"))
W <- spweights.constants(nb2listw(COL.nb, style="W"))
C <- spweights.constants(nb2listw(COL.nb, style="C"))
S <- spweights.constants(nb2listw(COL.nb, style="S"))
U <- spweights.constants(nb2listw(COL.nb, style="U"))
print(data.frame(rbind(unlist(B), unlist(W), unlist(C), unlist(S), unlist(U)),
  row.names=c("B", "W", "C", "S", "U")))

[Package spdep version 0.4-34 Index]