# Randomly Permute Time Points or Locations of `"epidataCS"`

`epidataCS_permute.Rd`

Monte Carlo tests for space-time interaction (`epitest`

)
use the distribution of some test statistic under the null hypothesis
of no space-time interaction. For this purpose, the function
`permute.epidataCS`

randomly permutes the time or space labels of
the events.

## Usage

`permute.epidataCS(x, what = c("time", "space"), keep)`

## Arguments

- x
an object of class

`"epidataCS"`

.- what
character string determining what to permute: time points (default) or locations.

- keep
optional logical expression to be evaluated in the context of

`x$events@data`

, determining for which events the time and location should be kept as is. For instance, to keep some “prehistory” before time point 30 unchanged, use`keep = time <= 30`

.

## Value

the permuted `"epidataCS"`

object.

## Examples

```
data("imdepi")
set.seed(3)
permepi <- permute.epidataCS(imdepi, what = "time", keep = time <= 30)
print(imdepi, n = 8)
print(permepi, n = 8)
## the first 6 events are kept (as are all row.names),
## the time labels of the remaining events are shuffled
## (and events then again sorted by time),
## the marginal temporal distribution is unchanged
```