The function tallies the numbers of neighbours of regions in the neighbours list.

card(nb)

## Arguments

nb

a neighbours list object of class nb

## Value

An integer vector of the numbers of neighbours of regions in the neighbours list.

## Details

“nb” objects are stored as lists of integer vectors, where the vectors contain either the indices in the range 1:n for n as length(nb) of the neighbours of region i, or as.integer(0) to signal no neighbours. The function card(nb) is used to extract the numbers of neighbours from the “nb” object.

## References

Bivand R, Pebesma EJ, Gomez-Rubio V, (2008) Applied Spatial Data Analysis with R, Springer, New York, pp. 239-251; Bivand R, Portnov B, (2004) Exploring spatial data analysis techniques using R: the case of observations with no neighbours. In: Anselin L, Florax R, Rey S, (eds.), Advances in Spatial Econometrics, Methodology, Tools and Applications. Berlin: Springer-Verlag, pp. 121-142.

## Author

Roger Bivand Roger.Bivand@nhh.no

summary.nb
col.gal.nb <- read.gal(system.file("weights/columbus.gal", package="spData")[1])