spatstat (version 1.63-0)

# rjitter: Random Perturbation of a Point Pattern

## Description

Applies independent random displacements to each point in a point pattern.

## Usage

`rjitter(X, radius, retry=TRUE, giveup = 10000, …, nsim=1, drop=TRUE)`

## Arguments

X

A point pattern (object of class `"ppp"`).

Scale of perturbations. A positive numerical value. The displacement vectors will be uniformly distributed in a circle of this radius. There is a sensible default.

retry

What to do when a perturbed point lies outside the window of the original point pattern. If `retry=FALSE`, the point will be lost; if `retry=TRUE`, the algorithm will try again.

giveup

Maximum number of unsuccessful attempts.

Ignored.

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.

## Value

A point pattern (an object of class `"ppp"`) if `nsim=1`, or a list of point patterns if `nsim > 1`, in the same window as `X`.

## Details

Each of the points in the point pattern `X` is subjected to an independent random displacement. The displacement vectors are uniformly distributed in a circle of radius `radius`.

If a displaced point lies outside the window, then if `retry=FALSE` the point will be lost.

However if `retry=TRUE`, the algorithm will try again: each time a perturbed point lies outside the window, the algorithm will reject it and generate another proposed perturbation of the original point, until one lies inside the window, or until `giveup` unsuccessful attempts have been made. In the latter case, any unresolved points will be included without any perturbation. The return value will always be a point pattern with the same number of points as `X`.

## Examples

```# NOT RUN {
X <- rsyst(owin(), 10, 10)
Y <- rjitter(X, 0.02)
plot(Y)
Z <- rjitter(X)
# }
```