# quadratresample

##### Resample a Point Pattern by Resampling Quadrats

Given a point pattern dataset, create a resampled point pattern by dividing the window into rectangular quadrats and randomly resampling the list of quadrats.

##### Usage

```
quadratresample(X, nx, ny=nx, ...,
replace = FALSE, nsamples = 1,
verbose = (nsamples > 1))
```

##### Arguments

- X
- A point pattern dataset (object of class
`"ppp"`

). - nx,ny
- Numbers of quadrats in the $x$ and $y$ directions.
- ...
- Ignored.
- replace
- Logical value. Specifies whether quadrats should be sampled with or without replacement.
- nsamples
- Number of randomised point patterns to be generated.
- verbose
- Logical value indicating whether to print progress reports.

##### Details

This command implements a very simple bootstrap resampling procedure
for spatial point patterns `X`

.

The dataset `X`

must be a point pattern (object of class
`"ppp"`

) and its observation window must be a rectangle.

The window is first divided into `N = nx * ny`

rectangular tiles
(quadrats) of equal size and shape.
To generate one resampled point pattern, a random sample of
`N`

quadrats is selected from the list of `N`

quadrats,
with replacement (if `replace=TRUE`

) or without replacement
(if `replace=FALSE`

). The $i$th quadrat in the original
dataset is then replaced by the $i$th sampled quadrat, after the
latter is shifted so that it
occupies the correct spatial position. The quadrats are then
reconstituted into a point pattern inside the same window as `X`

.

If `replace=FALSE`

, this procedure effectively involves a random
permutation of the quadrats. The resulting resampled point pattern has
the same number of points as `X`

.
If `replace=TRUE`

, the number of points in the resampled point
pattern is random.

##### Value

- A point pattern (if
`nsamples = 1`

) or a list of point patterns (if`nsamples > 1`

).

##### See Also

See `varblock`

to estimate the variance of
a summary statistic by block resampling.

##### Examples

```
data(bei)
quadratresample(bei, 6, 3)
```

*Documentation reproduced from package spatstat, version 1.41-1, License: GPL (>= 2)*