is.symmetric.nb {spdep} | R Documentation |
Checks a neighbours list for symmetry/transitivity (if i is a neighbour of j,
then j is a neighbour of i). This holds for distance and contiguity based
neighbours, but not for k-nearest neighbours. The helper function
sym.attr.nb()
calls is.symmetric.nb()
to set the sym
attribute if needed, and make.sym.nb
makes a non-symmetric list symmetric by adding neighbors. is.symmetric.glist
checks a list of general weights corresponding to neighbours for symmetry for symmetric neighbours.
is.symmetric.nb(nb, verbose = TRUE, force = FALSE) sym.attr.nb(nb) make.sym.nb(nb) is.symmetric.glist(nb, glist)
nb |
an object of class nb with a list of integer vectors containing neighbour region number ids. |
verbose |
if TRUE prints non-matching pairs |
force |
do not respect a neighbours list sym attribute and test anyway |
glist |
list of general weights corresponding to neighbours |
TRUE if symmetric, FALSE if not
Roger Bivand Roger.Bivand@nhh.no
data(columbus) print(is.symmetric.nb(col.gal.nb, verbose=TRUE, force=TRUE)) k4 <- knn2nb(knearneigh(coords, k=4), row.names=rownames(columbus)) k4 <- sym.attr.nb(k4) print(is.symmetric.nb(k4)) k4.sym <- make.sym.nb(k4) print(is.symmetric.nb(k4.sym))