# card

##### Cardinalities for neighbours lists

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

- Keywords
- spatial

##### Usage

`card(nb)`

##### Arguments

- nb
a neighbours list object of class

`nb`

##### 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.

##### Value

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

##### 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.

##### See Also

##### Examples

```
# NOT RUN {
col.gal.nb <- read.gal(system.file("weights/columbus.gal", package="spData")[1])
table(card(col.gal.nb))
# }
```

*Documentation reproduced from package spdep, version 1.1-3, License: GPL (>= 2)*