View source: R/linnetsurgery.R

thinNetwork | R Documentation |

Delete some vertices and/or segments from a linear network or related object.

thinNetwork(X, retainvertices, retainedges)

`X` |
A linear network (object of class |

`retainvertices` |
Optional. Subset index specifying which vertices should be retained (not deleted). |

`retainedges` |
Optional. Subset index specifying which edges (segments) should be retained (not deleted). |

This function deletes some of the vertices and edges (segments) in the linear network.

The arguments `retainvertices`

and `retainedges`

can be
any kind of subset index: a vector of positive integers specifying which
vertices/edges should be retained; a vector of negative integers
specifying which vertices/edges should be deleted; or a logical vector
specifying whether each vertex/edge should be retained (`TRUE`

)
or deleted (`FALSE`

).

Vertices are indexed in the same sequence as in
`vertices(as.linnet(X))`

.
Segments are indexed in the same sequence as in
`as.psp(as.linnet(X))`

.

The argument `retainedges`

has higher precedence than
`retainvertices`

in the sense that:

If

`retainedges`

is given, then any vertex which is an endpoint of a retained edge will also be retained.-
If

`retainvertices`

is given and`retainedges`

is**missing**, then any segment joining two retained vertices will also be retained. -
Thus, when both

`retainvertices`

and`retainedges`

are given, it is possible that more vertices will be retained than those specified by`retainvertices`

.

After the network has been altered, other consequential changes will
occur, including renumbering of the segments and vertices.
If `X`

is a point pattern on a linear network, then data points
will be deleted if they lie on a deleted edge.

An object of the same kind as `X`

.

and Suman Rakshit.

`linnet`

to make a network;

`connected.linnet`

to extract connected components.

`repairNetwork`

.

L <- simplenet plot(L, main="thinNetwork(L, retainedges=c(-3, -5))") text(midpoints.psp(as.psp(L)), labels=1:nsegments(L), pos=3) Lsub <- thinNetwork(L, retainedges=c(-3, -5)) plot(Lsub, add=TRUE, col="blue", lwd=2)

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