This function generates n
independent random points,
uniformly distributed in the window win
.
(For nonuniform distributions, see rpoint
.)
The algorithm depends on the type of window, as follows:
If win
is a rectangle then
\(n\) independent random points, uniformly distributed
in the rectangle, are generated by assigning uniform random values to their
cartesian coordinates.
If win
is a binary image mask, then a random sequence of
pixels is selected (using sample
)
with equal probabilities. Then for each pixel in the sequence
we generate a uniformly distributed random point in that pixel.
If win
is a polygonal window, the algorithm uses the rejection
method. It finds a rectangle enclosing the window,
generates points in this rectangle, and tests whether they fall in
the desired window. It gives up when giveup * n
tests
have been performed without yielding n
successes.
The algorithm for binary image masks is faster than the rejection
method but involves discretisation.
If warn=TRUE
, then a warning will be issued if n
is very large.
The threshold is spatstat.options("huge.npoints")
.
This warning has no consequences,
but it helps to trap a number of common errors.