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Computes quadrature weights for a given set of points, using the areas of tiles in the Dirichlet tessellation.
dirichletWeights(X, window=NULL, exact=TRUE, …)Data defining a point pattern.
Default window for the point pattern
Logical value. If TRUE, compute exact areas
using the package deldir. If FALSE, compute
approximate areas using a pixel raster.
Ignored.
Vector of nonnegative weights for each point in X.
This function computes a set of quadrature weights
for a given pattern of points
(typically comprising both ``data'' and `dummy'' points).
See quad.object for an explanation of quadrature
weights and quadrature schemes.
The weights are computed using the Dirichlet tessellation.
First X and (optionally) window are converted into a
point pattern object. Then the Dirichlet tessellation of the points
of X is computed.
The weight attached to a point of X is the area of
its Dirichlet tile (inside the window Window(X)).
If exact=TRUE the Dirichlet tessellation is computed exactly
by the Lee-Schachter algorithm using the package deldir.
Otherwise a pixel raster approximation is constructed and the areas
are approximations to the true weights. In all cases the sum of the
weights is equal to the area of the window.
# NOT RUN {
Q <- quadscheme(runifpoispp(10))
X <- as.ppp(Q) # data and dummy points together
w <- dirichletWeights(X, exact=FALSE)
# }
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