Create a Linear Network
Creates an object of class
a network of line segments.
linnet(vertices, m, edges, sparse=FALSE)
- Point pattern (object of class
"ppp") specifying the vertices of the network.
- Adjacency matrix. A matrix or sparse matrix
of logical values equal to
TRUEwhen the corresponding vertices are joined by a line. (Specify either
- Edge list. A two-column matrix of integers,
specifying all pairs of vertices
that should be joined by an edge.
- Optional. Logical value indicating whether to use a sparse matrix representation of the network. See Details.
An object of class
"linnet" represents a network of
straight line segments in two dimensions. The function
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.
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.
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
- Object of class
"linnet"representing the linear network.
simplenet for an example of a linear network.
methods applicable to
# 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)