Sector K-function
A directional counterpart of Ripley's K function, in which pairs of points are counted only when the vector joining the pair happens to lie in a particular range of angles.
Ksector(X, begin = 0, end = 360, ...,
units = c("degrees", "radians"),
r = NULL, breaks = NULL,
correction = c("border", "isotropic", "Ripley", "translate"),
domain=NULL, ratio = FALSE, verbose=TRUE)X |
The observed point pattern,
from which an estimate of K(r) will be computed.
An object of class |
begin,end |
Numeric values giving the range of angles inside which
points will be counted. Angles are measured in degrees
(if |
... |
Ignored. |
units |
Units in which the angles |
r |
Optional. Vector of values for the argument r at which K(r) should be evaluated. Users are advised not to specify this argument; there is a sensible default. |
breaks |
This argument is for internal use only. |
correction |
Optional. A character vector containing any selection of the
options |
domain |
Optional window. The first point x[i] of each pair of points
will be constrained to lie in |
ratio |
Logical.
If |
verbose |
Logical value indicating whether to print progress reports and warnings. |
This is a directional counterpart of Ripley's K function
(see Kest) in which, instead of counting all
pairs of points within a specified distance r, we
count only the pairs x[i], x[j]
for which the vector x[j] - x[i]
falls in a particular range of angles.
This can be used to evaluate evidence for anisotropy
in the point pattern X.
An object of class "fv" containing the estimated
function.
Adrian Baddeley Adrian.Baddeley@curtin.edu.au
Rolf Turner r.turner@auckland.ac.nz
and Ege Rubak rubak@math.aau.dk
K <- Ksector(swedishpines, 0, 90) plot(K)
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