Neighbours list: type Rook contiguity

nb2 <- poly2nb(map_geom, queen = FALSE)
nb2

## Neighbour list object:
## Number of regions: 49 
## Number of nonzero links: 200 
## Percentage nonzero weights: 8.329863 
## Average number of links: 4.081633

head(nb2)

## [[1]]
## [1] 2 3
## 
## [[2]]
## [1] 1 3 4
## 
## [[3]]
## [1] 1 2 4 5
## 
## [[4]]
## [1] 2 3 5 8
## 
## [[5]]
## [1]  3  4  6  8  9 11 15
## 
## [[6]]
## [1] 5 9