spatstat (version 1.44-0)

nnwhich.lpp: Identify Nearest Neighbours on a Linear Network

Description

Given a pattern of points on a linear network, identify the nearest neighbour for each point, measured by the shortest path in the network.

Usage

## S3 method for class 'lpp':
nnwhich(X, ..., k=1, method="C")

Arguments

X

Point pattern on linear network (object of class "lpp").

method

Optional string determining the method of calculation. Either "interpreted" or "C".

k

Integer, or integer vector. The algorithm will find the kth nearest neighbour.

...

Ignored.

Value

• An integer vector, of length equal to the number of points in X, identifying the nearest neighbour of each point. If nnwhich(X)[2] = 4 then the nearest neighbour of point 2 is point 4.

  Alternatively a matrix with one row for each point in X and one column for each entry of k.

Details

Given a pattern of points on a linear network, this function finds the nearest neighbour of each point (i.e. for each point it identifies the nearest other point) measuring distance by the shortest path in the network. If method="C" the task is performed using code in the C language. If method="interpreted" then the computation is performed using interpreted Rcode. The Rcode is much slower, but is provided for checking purposes.

See Also

lpp

Examples

example(lpp)
   nnwhich(X)
   nnwhich(X, k=2)