Empirical ROC surface plot — rocsurf.emp • trinROC

Function for computation of the empirical ROC surface.

rocsurf.emp(x, y, z, plot = TRUE, saveVUS = FALSE)

Arguments

x, y, z: Vectors containing the data of the three classes "healthy", "intermediate" and "diseased".
plot: logical. If TRUE (default), the VUS is plotted using surface3d from the package rgl.
saveVUS: A logical whether to save a PNG of the VUS in your current working directory (default is FALSE).

Value

A list with the following components:

t1, t2, zVUS: The matice containing the surface values.
x, y, z: The original data.

Details

This function takes three-class ROC data and computes the three dimentional surface using the R-package rgl. The ROC surface is defined as

$$z = ROCs(t_-,t_+) = F_0(c_+) - F_0(c_-)=F_0(G_+^{-1}(t_+) ) -F_0(F_-^{-1}(t_-) ),$$

where \(c_-, c_+\) are the two cut-off points and \(F_-, F_0, F_+\) the cdf of the three classes with \(G = 1-F\).

See also

Examples

data(cancer)
x1 <- with(cancer, cancer[trueClass=="healthy", 9])
y1 <- with(cancer, cancer[trueClass=="intermediate", 9])
z1 <- with(cancer, cancer[trueClass=="diseased", 9])

rocsurf.emp(x1, y1, z1)