Compute area of intersection between a disc and a window
discpartarea(X, r, W=as.owin(X))Numeric matrix, with one row for each point of X.
Point pattern (object of class "ppp")
specifying the centres of the discs.
Alternatively, X may be in any format
acceptable to as.ppp.
Matrix, vector or numeric value specifying the radii of the discs.
Window (object of class "owin") with which the
discs should be intersected.
Adrian Baddeley Adrian.Baddeley@curtin.edu.au and Rolf Turner r.turner@auckland.ac.nz
This algorithm computes the exact area of the intersection between
a window W and a disc (or each of several discs).
The centres of the discs are specified by the point pattern
X, and their radii are specified by r.
If r is a single numeric value, then the algorithm computes the
area of intersection between W and the disc of radius r centred
at each point of X, and returns a one-column matrix
containing one entry for each point of X.
If r is a vector of length m, then the algorithm
returns an n * m matrix in which the entry on row i,
column j is the area of the
intersection between W and the disc centred at X[i]
with radius r[j].
If r is a matrix, it should have one row for each point in
X. The algorithm
returns a matrix in which the entry on row i,
column j is the area of the
intersection between W and the disc centred at X[i]
with radius r[i,j].
Areas are computed by analytic geometry.
owin,
disc
X <- unmark(demopat)[1:3]
discpartarea(X, 0.2)
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