disc

0th

Percentile

Circular Window

Creates a circular window

Keywords
spatial, datagen
Usage
disc(radius=1, centre=c(0,0), ..., mask=FALSE, npoly=128)
Arguments
radius
Radius of the circle.
centre
Coordinates of the centre of the circle.
mask
Logical flag controlling the type of approximation to a perfect circle. See Details.
npoly
Number of edges of the polygonal approximation, if mask=FALSE.
...
Arguments passed to as.mask determining the pixel resolution, if mask=TRUE.
Details

This command creates a window object representing a disc, with the given radius and centre.

By default, the circle is approximated by a polygon with npoly edges.

If mask=TRUE, then the disc is approximated by a binary pixel mask. The resolution of the mask is controlled by the arguments ... which are passed to as.mask.

Value

  • An object of class "owin" (see owin.object) specifying a window.

Note

This function can also be used to generate regular polygons, by setting npoly to a small integer value. For example npoly=5 generates a pentagon and npoly=13 a triskaidecagon.

See Also

owin.object, owin, as.mask

Aliases
  • disc
Examples
# unit disc
 W <- disc()
 # disc of radius 3 centred at x=10, y=5
 W <- disc(3, c(10,5))
 #
 plot(disc())
 plot(disc(mask=TRUE))
 # nice smooth circle
 plot(disc(npoly=256))
 # how to control the resolution of the mask
 plot(disc(mask=TRUE, dimyx=256))
 # check accuracy of approximation
 area.owin(disc())/pi
 area.owin(disc(mask=TRUE))/pi
Documentation reproduced from package spatstat, version 1.17-0, License: GPL (>= 2)

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