vandalico (version 0.2.0)

HSgraph: Suitability values distribution graph

Description

A function to visualize the distribution of the suitability values associated to presences, absences, and all cases together.

Usage

HSgraph(mat, breaks = 10, hist.total = TRUE)

Value

This function returns a multiple histogram.

Arguments

mat

A matrix with two columns. The first column must contain the suitability values (i.e., the classification rule); the second column must contain the presences and absences.

breaks

Number of cells for the total histogram. By default, breaks = 10.

hist.total

Logical. Indicates whether or not the distribution of suitability values for all the cases together is graphed.

Details

In blue, the distribution of the suitability values associated to presences. In red, the distribution of the suitability values associated to absences. This graph helps to understand why the AUC (or Se*) is greater, equal to, or less than the uAUC (or uSe*) (see Jiménez-Valverde 2022).

References

Jiménez-Valverde, A. (2022). The uniform AUC: dealing with the representativeness effect in presence-absence models. Methods Ecol. Evol., 13, 1224-1236.

Examples

suit<-rbeta(100, 2, 2) # Generate suitability values
random<-runif(100)
sp<-ifelse(random < suit, 1 , 0) # Generate presence-absence data
HSgraph(cbind(suit, sp), breaks = 20, hist.total = TRUE)