spdep (version 1.3-6)

spweights.constants: 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=attr(listw, "zero.policy"), adjust.n=TRUE)
Szero(listw)

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

Arguments

listw

a listw object from for example nb2listw

zero.policy

default attr(listw, "zero.policy") as set when listw was created, if attribute not set, use global option value; 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

Author

Roger Bivand

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")))