R: Adjacency structure of the counties in the contiguous United...
UScounties
R Documentation
Adjacency structure of the counties in the contiguous United States
Description
First and second order adjacency structure of the counties
in the contiguous United States. We consider that two counties
are neighbors if they share at
least one edge of their polygon description in maps.
Format
Two matrices of class spam
UScounties.storder
Contains a one in the i and j element if county
i is a neighbor of county j.
UScounties.ndorder
Contains a one in the i and j element if counties
i and j are a neighbors of county k and counties
i and j are not neighbors.
See Also
map from maps.
Examples
# number of counties:
n <- nrow( UScounties.storder)
## Not run:
# make a precision matrix
Q <- diag.spam( n) + .2 * UScounties.storder + .1 * UScounties.ndorder
display( as.spam( chol( Q)))
## End(Not run)