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)The observed point pattern,
from which an estimate of \(K(r)\) will be computed.
An object of class "ppp", or data
in any format acceptable to as.ppp().
Numeric values giving the range of angles inside which
points will be counted. Angles are measured in degrees
(if units="degrees", the default) or radians
(if units="radians") anti-clockwise from the positive \(x\)-axis.
Ignored.
Units in which the angles begin and end are expressed.
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.
This argument is for internal use only.
Optional. A character vector containing any selection of the
options "none", "border", "bord.modif",
"isotropic", "Ripley", "translate",
"translation", "none", "good" or "best".
It specifies the edge correction(s) to be applied.
Alternatively correction="all" selects all options.
Optional window. The first point \(x_i\) of each pair of points
will be constrained to lie in domain.
Logical.
If TRUE, the numerator and denominator of
each edge-corrected estimate will also be saved,
for use in analysing replicated point patterns.
Logical value indicating whether to print progress reports and warnings.
An object of class "fv" containing the estimated
function.
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.
# NOT RUN {
K <- Ksector(swedishpines, 0, 90)
plot(K)
# }
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