# rsyst

##### Simulate systematic random point pattern

Generates a “systematic random” pattern of points in a window, consisting of a grid of equally-spaced points with a random common displacement.

##### Usage

```
rsyst(win=square(1), nx=NULL, ny=nx, …, dx=NULL, dy=dx,
nsim=1, drop=TRUE)
```

##### Arguments

- win
A window. An object of class

`owin`

, or data in any format acceptable to`as.owin()`

.- nx
Number of columns of grid points in the window. Incompatible with

`dx`

.- ny
Number of rows of grid points in the window. Incompatible with

`dy`

.- …
Ignored.

- dx
Spacing of grid points in \(x\) direction. Incompatible with

`nx`

.- dy
Spacing of grid points in \(y\) direction. Incompatible with

`ny`

.- 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.

##### Details

This function generates a “systematic random” pattern
of points in the window `win`

. The pattern consists of a
rectangular grid of points with a random common displacement.

The grid spacing in the \(x\) direction is determined
either by the number of columns `nx`

or by the
horizontal spacing `dx`

.
The grid spacing in the \(y\) direction is determined
either by the number of rows `ny`

or by the
vertical spacing `dy`

.

The grid is then given a random displacement (the common displacement
of the grid points is a uniformly distributed random vector in the
tile of dimensions `dx, dy`

).

Some of the resulting grid points may lie outside the window
`win`

: if they do, they are deleted. The result is a point
pattern inside the window `win`

.

This function is useful in creating dummy points for quadrature
schemes (see `quadscheme`

) as well as in simulating
random point patterns.

##### Value

A point pattern (an object of class `"ppp"`

)
if `nsim=1`

, or a list of point patterns if `nsim > 1`

.

##### See Also

##### Examples

```
# NOT RUN {
X <- rsyst(nx=10)
plot(X)
# polygonal boundary
data(letterR)
X <- rsyst(letterR, 5, 10)
plot(X)
# }
```

*Documentation reproduced from package spatstat, version 1.62-2, License: GPL (>= 2)*