lineardisc {spatstat} | R Documentation |
Computes the ‘disc’ of given radius and centre in a linear network.
lineardisc(L, x = locator(1), r, plotit = TRUE, cols=c("blue", "red","green")) countends(L, x = locator(1), r)
L |
Linear network (object of class |
x |
Location of centre of disc.
Either a point pattern (object of class |
r |
Radius of disc. |
plotit |
Logical. Whether to plot the disc. |
cols |
Colours for plotting the disc. A numeric or character vector of length 3 specifying the colours of the disc centre, disc lines and disc endpoints respectively. |
The ‘disc’ B(u,r) of centre x and radius r in a linear network L is the set of all points u in L such that the shortest path distance from x to u is less than or equal to r. This is a union of line segments contained in L.
The relative boundary of the disc B(u,r) is the set of points v such that the shortest path distance from x to u is equal to r.
The function lineardisc
computes the
disc of radius r and its relative boundary,
optionally plots them, and returns them.
The faster function countends
simply counts the number of
points in the relative boundary.
The value of lineardisc
is a list with two entries:
lines |
Line segment pattern (object of class |
endpoints |
Point pattern (object of class |
The value of countends
is an integer giving the number of
points in the relative boundary.
Ang Qi Wei aqw07398@hotmail.com and Adrian Baddeley Adrian.Baddeley@csiro.au http://www.maths.uwa.edu.au/~adrian/
Ang, Q.W. (2010) Statistical methodology for events on a network. Master's thesis, School of Mathematics and Statistics, University of Western Australia.
Ang, Q.W., Baddeley, A. and Nair, G. (2012) Geometrically corrected second-order analysis of events on a linear network, with applications to ecology and criminology. To appear in Scandinavian Journal of Statistics.
example(linnet) lineardisc(letterA, c(0,3), 1.6) # count the endpoints countends(letterA, c(0,3), 1.6) # cross-check (slower) lineardisc(letterA, c(0,3), 1.6, plotit=FALSE)$endpoints$n