card | R Documentation |

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

```
card(nb)
```

`nb` |
a neighbours list object of class |

“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.

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

Roger Bivand Roger.Bivand@nhh.no

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.

`summary.nb`

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

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