# plot.kstest

##### Plot a Spatial Kolmogorov-Smirnov Test

Plot the result of a spatial Kolmogorov-Smirnov test

##### Usage

```
## S3 method for class 'kstest':
plot(x, ...,
style=c("cdf", "PP", "QQ"),
lwd=par("lwd"), col=par("col"), lty=par("lty"),
lwd0=lwd, col0=col, lty0=lty)
```

##### Arguments

- x
- Object to be plotted. An object of class
`"kstest"`

produced by a method for`kstest`

. - ...
- extra arguments that will be passed to the plotting function
`plot.default`

. - style
- Style of plot. See Details.
- col,lwd,lty
- The width, colour and type of lines used to plot the empirical curve (the empirical distribution, or PP plot or QQ plot).
- col0,lwd0,lty0
- The width, colour and type of lines used to plot the reference curve (the predicted distribution, or the diagonal).

##### Details

This is the `plot`

method for the class `"kstest"`

.
An object of this class represents the outcome of
a spatial Kolmogorov-Smirnov test, computed by `kstest`

.

If `style="cdf"`

(the default),
the plot displays the two cumulative distribution functions
that are compared by the test: namely the empirical cumulative distribution
function of the covariate at the data points, and the predicted
cumulative distribution function of the covariate under the model,
both plotted against the value of the covariate. The
Kolmogorov-Smirnov test statistic is the maximum vertical separation
between the two curves.

If `style="PP"`

then the P-P plot is drawn. The
$x$ coordinates of the plot are cumulative
probabilities for the covariate under the model.
The $y$ coordinates are cumulative probabilities
for the covariate at the data points. The diagonal line
$y=x$ is also drawn for reference. The Kolmogorov-Smirnov
test statistic is the maximum vertical separation
between the P-P plot and the diagonal reference line.

If `style="QQ"`

then the Q-Q plot is drawn. The
$x$ coordinates of the plot are quantiles
of the covariate under the model.
The $y$ coordinates are quantiles of the
covariate at the data points. The diagonal line
$y=x$ is also drawn for reference. The Kolmogorov-Smirnov
test statistic cannot be read off the Q-Q plot.

##### Value

`NULL`

.

##### See Also

##### Examples

```
# synthetic data: nonuniform Poisson process
X <- rpoispp(function(x,y) { 100 * exp(x) }, win=square(1))
# fit uniform Poisson process
fit0 <- ppm(X, ~1)
# test covariate = x coordinate
xcoord <- function(x,y) { x }
# test wrong model
k <- kstest(fit0, xcoord)
# plot result of test
plot(k, lwd0=3)
plot(k, style="PP")
plot(k, style="QQ")
```

*Documentation reproduced from package spatstat, version 1.31-3, License: GPL (>= 2)*