Generates a quadrature scheme (an object of class "quad"
)
on a linear network.
linequad(X, Y, …, eps = NULL, nd = 1000, random = FALSE)
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.
Optional. Total number of dummy points to be generated.
Logical value indicating whether the sequence of dummy points should start at a randomly-chosen position along each segment.
A quadrature scheme (object of class "quad"
).
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.