Generates a quadrature scheme (an object of class "quad")
on a linear network.
linequad(X, Y, ..., eps = NULL, nd = 1000, random = FALSE)A quadrature scheme (object of class "quad").
Data points. An object of class "lpp" or "ppp".
Line segments on which the points of X lie.
An object of class "psp".
Required only when X is a "ppp" object.
Ignored.
Optional. Spacing between successive dummy points along each segment. (This is the maximum spacing; some spacings will be shorter.)
Optional. Total number of dummy points to be generated. (Actual number may be larger.)
Logical value indicating whether the sequence of dummy points should start at a randomly-chosen position along each segment.
Adrian Baddeley Adrian.Baddeley@curtin.edu.au, Greg McSwiggan and Suman Rakshit.
This command generates a quadrature scheme (object of class
"quad") from a pattern of points on a linear network.
Normally the user does not need to call linequad explicitly.
It is invoked by spatstat functions when needed.
A quadrature scheme is required by lppm
in order to fit point process models to point pattern data on a linear
network. A quadrature scheme is also used by rhohat.lpp
and other functions.
In order to create the quadrature scheme, dummy points are placed
along each line segment of the network. The dummy points are
evenly-spaced with spacing eps. The default is
eps = totlen/nd where totlen is the total length of
all line segments in the network.
Every line segment of the network will contain at least one dummy
point. Consequently the actual number of dummy points generated
will typically be greater than nd,
especially when nd is small.
If eps is specified, the
number of dummy points will be greater than totlen/eps,
especially when eps is large.
lppm