addVertices {spatstat.linnet}

Add New Vertices to a Linear Network

Description

Adds new vertices to a linear network at specified locations outside the network.

Usage

addVertices(L, X, join=NULL, joinmarks=NULL)

Arguments

L

Existing linear network (object of class "linnet") or point pattern on a linear network (object of class "lpp").

X

Point pattern (object of class "ppp") specifying the new vertices.

join

Optional information specifying how to join the new vertices X to the existing network. See Details. If join=NULL (the default), the new vertices are simply added to the list of network vertices without being joined to the rest of the network.

joinmarks

Optional vector or data frame of marks associated with the new edges specified by join.

Details

This function adds new vertices to an existing linear network L, at specified locations X outside the network.

The argument L can be either a linear network (class "linnet") or some other object that includes a linear network.

The new vertex locations are points outside the network, specified as a point pattern X (object of class "ppp").

The argument join specifies how to join the new vertices to the existing network.

• If join=NULL (the default), the new vertices are simply added to the list of network vertices without being joined to the rest of the network.

• If join is a vector of integers, then these are taken to be indices of existing vertices of L in the order given in V = vertices(L). Then each new vertex X[i] will be joined to an existing vertex V[j] where j = join[i]. Each new vertex is joined to exactly one existing vertex.

• If join="vertices" then each new vertex X[i] is joined to the nearest existing vertex V[j]. Each new vertex is joined to exactly one existing vertex.

• If join="nearest" then each new vertex is projected to the nearest location along on the network; these locations are inserted as new vertices of L; and then each vertex X[i] is joined to the corresponding projected point. Each new vertex is joined to exactly one newly-inserted vertex.

• If join is a point pattern on a network (class "lpp"), it must be defined on the same network as L and it must consist of the same number of points as X. The points of join will be inserted as new vertices of L, and then each vertex X[i] is joined to the corresponding point join[i]. Each new vertex is joined to exactly one newly-inserted vertex.

The result is the modified object, with an attribute "id" such that the ith added vertex has become the id[i]th vertex of the new network.

Value

An object of the same class as L representing the result of adding the new vertices. The result also has an attribute "id" as described in Details.

Author(s)

Adrian Baddeley

See Also

insertVertices to insert vertices along an existing network.

as.lpp, linnet, methods.linnet, joinVertices, thinNetwork.

Examples

   opa <- par(mfrow=c(1,3))
   L <- simplenet
   X <- runifpoint(20, Window(simplenet))
   plot(L)
   plot(X, add=TRUE, cols="green", pch=16, cex=2)
   plot(addVertices(L, X, "nearest"), col="red")
   plot(L, add=TRUE, col="grey", lwd=3)
   plot(X, add=TRUE, cols="green", pch=16, cex=2)
   plot(addVertices(L, X, "vertices"), col="red")
   plot(L, add=TRUE, col="grey", lwd=3)
   plot(X, add=TRUE, cols="green", pch=16, cex=2)
   par(opa)