spatstat (version 1.64-1)

plot.scan.test: Plot Result of Scan Test

Description

Computes or plots an image showing the likelihood ratio test statistic for the scan test, or the optimal circle radius.

Usage

# S3 method for scan.test
plot(x, …, what=c("statistic", "radius"),
               do.window = TRUE)
 # S3 method for scan.test
as.im(X, …, what=c("statistic", "radius"))

Arguments

x,X

Result of a scan test. An object of class "scan.test" produced by scan.test.

…

Arguments passed to plot.im to control the appearance of the plot.

what

Character string indicating whether to produce an image of the (profile) likelihood ratio test statistic (what="statistic", the default) or an image of the optimal value of circle radius (what="radius").

do.window

Logical value indicating whether to plot the original window of the data as well.

Value

The value of as.im.scan.test is a pixel image (object of class "im"). The value of plot.scan.test is NULL.

Details

These functions extract, and plot, the spatially-varying value of the likelihood ratio test statistic which forms the basis of the scan test.

If the test result X was based on circles of the same radius r, then as.im(X) is a pixel image of the likelihood ratio test statistic as a function of the position of the centre of the circle.

If the test result X was based on circles of several different radii r, then as.im(X) is a pixel image of the profile (maximum value over all radii r) likelihood ratio test statistic as a function of the position of the centre of the circle, and as.im(X, what="radius") is a pixel image giving for each location \(u\) the value of r which maximised the likelihood ratio test statistic at that location.

The plot method plots the corresponding image.

See Also

scan.test, scanLRTS

Examples

# NOT RUN {
   if(interactive()) {
     a <- scan.test(redwood, seq(0.04, 0.1, by=0.01),
                    method="poisson", nsim=19)
   } else {
     a <- scan.test(redwood, c(0.05, 0.1), method="poisson", nsim=2)
   }
   plot(a)
   as.im(a)
   plot(a, what="radius")
# }