| pairorient {spatstat} | R Documentation |
Computes the distribution of the orientation of vectors joining pairs of points at a particular range of distances.
pairorient(X, r1, r2, ..., correction, ratio = FALSE)
X |
Point pattern (object of class |
r1,r2 |
Minimum and maximum values of distance to be considered. |
... |
Ignored. |
correction |
Character vector specifying edge correction or corrections.
Options are |
ratio |
Logical.
If |
This function calculates the point pair orientation distribution function O[r1,r2](phi) defined in Stoyan and Stoyan (1994), equation (14.53), page 271.
The function considers all pairs of points in the pattern
X that lie more than r1 and less than r2
units apart. The direction of the arrow joining the points
is measured, as an angle in degrees, anticlockwise from the x axis.
The result is the cumulative distribution function of these
directions.
In calculating the cumulative distribution function,
the algorithm gives each observed direction a weight,
determined by an edge correction, to adjust for the fact that some
interpoint distances are more likely to be observed than others.
The choice of edge correction or corrections is determined by the argument
correction.
To calculate the probability density of directions,
use deriv.fv with the argument Dperiodic=TRUE.
A function value table (object of class "fv")
containing the estimates of the cumulative distribution
function of angles, in degrees.
Adrian Baddeley Adrian.Baddeley@uwa.edu.au Rolf Turner r.turner@auckland.ac.nz and Ege Rubak rubak@math.aau.dk
Stoyan, D. and Stoyan, H. (1994) Fractals, random shapes and point fields: methods of geometrical statistics. John Wiley and Sons.
plot(f <- pairorient(redwood, 0.05, 0.15)) plot(Df <- deriv(f, spar=0.6, Dperiodic=TRUE))