# linnet

##### Create a Linear Network

Creates an object of class `"linnet"`

representing
a network of line segments.

- Keywords
- spatial

##### Usage

`linnet(vertices, m, edges, sparse=FALSE, warn=TRUE)`

##### Arguments

- vertices
Point pattern (object of class

`"ppp"`

) specifying the vertices of the network.- m
Adjacency matrix. A matrix or sparse matrix of logical values equal to

`TRUE`

when the corresponding vertices are joined by a line. (Specify either`m`

or`edges`

.)- edges
Edge list. A two-column matrix of integers, specifying all pairs of vertices that should be joined by an edge. (Specify either

`m`

or`edges`

.)- sparse
Optional. Logical value indicating whether to use a sparse matrix representation of the network. See Details.

- warn
Logical value indicating whether to issue a warning if the resulting network is not connected.

##### Details

An object of class `"linnet"`

represents a network of
straight line segments in two dimensions. The function `linnet`

creates
such an object from the minimal information: the spatial location
of each vertex (endpoint, crossing point or meeting point of lines)
and information about which vertices are joined by an edge.

If `sparse=FALSE`

(the default), the algorithm will compute
and store various properties of the network, including
the adjacency matrix `m`

and a matrix giving the
shortest-path distances between each pair of vertices in the network.
This is more efficient for small datasets. However it can require
large amounts of memory and can take a long time to execute.

If `sparse=TRUE`

, then the shortest-path distances will not be computed,
and the network adjacency matrix `m`

will be stored as a
sparse matrix. This saves a lot of time and memory when creating the
linear network.

If the argument `edges`

is given, then it will also determine
the *ordering* of the line segments when they are stored or extracted.
For example, `edges[i,]`

corresponds to `as.psp(L)[i]`

.

##### Value

Object of class `"linnet"`

representing the linear network.

##### See Also

`simplenet`

for an example of a linear network.

`methods.linnet`

for
methods applicable to `linnet`

objects.

Special tools: `thinNetwork`

,
`insertVertices`

,
`joinVertices`

,
`connected.linnet`

, `lixellate`

.

`delaunayNetwork`

for the Delaunay triangulation
as a network.

##### Examples

```
# NOT RUN {
# letter 'A' specified by adjacency matrix
v <- ppp(x=(-2):2, y=3*c(0,1,2,1,0), c(-3,3), c(-1,7))
m <- matrix(FALSE, 5,5)
for(i in 1:4) m[i,i+1] <- TRUE
m[2,4] <- TRUE
m <- m | t(m)
letterA <- linnet(v, m)
plot(letterA)
# letter 'A' specified by edge list
edg <- cbind(1:4, 2:5)
edg <- rbind(edg, c(2,4))
letterA <- linnet(v, edges=edg)
# }
```

*Documentation reproduced from package spatstat, version 1.57-1, License: GPL (>= 2)*