runifdisc: Generate N Uniform Random Points in a Disc

In spatstat.random: Random Generation Functionality for the 'spatstat' Family

Generate N Uniform Random Points in a Disc

Description

Generate a random point pattern containing n independent uniform random points in a circular disc.

Usage

 runifdisc(n, radius=1, centre=c(0,0), ..., nsim=1, drop=TRUE, boxed=FALSE)

Arguments

n	Number of points.
radius	Radius of the circle.
centre	Coordinates of the centre of the circle.
...	Arguments passed to disc controlling the accuracy of approximation to the circle.
nsim	Number of simulated realisations to be generated.
drop	Logical. If nsim=1 and drop=TRUE (the default), the result will be a point pattern, rather than a list containing a point pattern.
boxed	Logical value indicating whether to replace the disc window by a square window, for computational efficiency.

Details

This function generates n independent random points, uniformly distributed in a circular disc.

It is faster (for a circular window) than the general code used in runifpoint.

To generate random points in an ellipse, first generate points in a circle using runifdisc, then transform to an ellipse using affine, as shown in the examples.

To generate random points in other windows, use runifpoint. To generate non-uniform random points, use rpoint.

Value

A point pattern (an object of class "ppp") if nsim=1, or a list of point patterns if nsim > 1.

Speed of computation

The random point coordinates are generated by a very fast algorithm.

Computation time includes the time taken to construct the circular window containing the resulting point pattern, which is generated by disc. Arguments passed to disc control the accuracy of the polygonal approximation to the circle, and therefore affect the computation time.

If boxed=TRUE, the circular window is not constructed, and is replaced by a square window, which is much faster to compute. The random points are still generated uniformly inside the disc by the same fast algorithm.

Author(s)

\adrian

and \rolf.

See Also

disc, runifpoint, rpoint

Examples

 # 100 random points in the unit disc
 plot(runifdisc(100))
 # 42 random points in the ellipse with major axis 3 and minor axis 1
 X <- runifdisc(42)
 Y <- affine(X, mat=diag(c(3,1)))
 plot(Y)

spatstat.random documentation built on Nov. 21, 2025, 9:07 a.m.