Union of Discs
Make a spatial region composed of discs with given centres and radii.
discs(centres, radii = marks(centres)/2, ..., separate = FALSE, mask = FALSE, trim = TRUE, delta = NULL)
- Point pattern giving the locations of centres for the discs.
- Vector of radii for each disc, or a single number giving a common
(Notice that the default assumes that the marks of
- Optional arguments passed to
as.maskto determine the pixel resolution, if
- Logical. If
TRUE, the result is a list containing each disc as a separate entry. If
FALSE(the default), the result is a window obtained by forming the union of the discs.
- Logical. If
TRUE, the result is a binary mask window. If
FALSE, the result is a polygonal window. Applies only when
- Logical value indicating whether to restrict the result
to the original window of the
centres. Applies only when
- Argument passed to
discto determine the tolerance for the polygonal approximation of each disc. Applies only when
This command is typically applied to a marked point pattern
X in which the marks represent the sizes of objects.
The result is a spatial region representing the space occupied by
If the marks of
X represent the diameters of circular objects,
then the result of
is a spatial region constructed by taking discs, of the specified
diameters, centred at the points of
X, and forming the union
of these discs. If the marks of
X represent the areas of
objects, one could take
to produce discs of equivalent area.
A fast algorithm is used to compute the result as a binary mask, when
mask=TRUE. This option is recommended unless polygons are
mask=FALSE, the discs will be constructed as polygons
by the function
disc. To avoid computational problems, the discs
will all be constructed using the same physical tolerance value
disc. The default is such that the smallest
disc will be approximated by a 16-sided polygon.
separate=FALSE, a window (object of class
separate=TRUE, a list of windows.
plot(discs(anemones, mask=TRUE, eps=0.5))