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
- Numeric values giving the range of angles inside which
points will be counted. Angles are measured in degrees
units="degrees", the default) or radians (if
units="radians") anti-clockwise from the positive $x$-axis
- Units in which the angles
- 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
- Optional window. The first point $x_i$ of each pair of points
will be constrained to lie in
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.
This is a directional counterpart of Ripley's $K$ function
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
- An object of class
"fv"containing the estimated function.
K <- Ksector(swedishpines, 0, 90) plot(K)