# 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, ny=nx, dx=NULL, dy=NULL)`

##### Arguments

- win
- A window.
An object of class
`owin`

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

. - dx
- Spacing of grid points in $x$ direction.
Incompatible with
`nx`

. - dy
- Spacing of grid points in $y$ direction.
Incompatible with
`ny`

. - 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`

.

##### Details

This function generates a `win`

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

The grid spacing is determined by the distances `dx, dy`

if they are present. If they are absent, then the grid spacing is
determined so that there will be `nx`

columns and `ny`

rows
of grid points in the bounding rectangle of `win`

.

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 (object of class
`"ppp"`

).

##### See Also

##### Examples

```
X <- rsyst(nx=10)
plot(X)
# polygonal boundary
data(letterR)
X <- rsyst(letterR, 5, 10)
plot(X)
```

*Documentation reproduced from package spatstat, version 1.10-2, License: GPL version 2 or newer*