dismo (version 1.1-1)

threshold: Find a threshold

Description

Find a threshold (cut-off) to transform model predictions (probabilities, distances, or similar values) to a binary score (presence or absence).

Usage

"threshold"(x, stat='', sensitivity=0.9, ...)

Arguments

x

A ModelEvaluation object (see evaluate

stat

character. To select a particular threshold (see section 'value' for possible values)

sensitivity

numeric between 0 and 1. For the fixed sensitivity threshold

...

Additional arguments. None implemented

Value

data.frame with the following columns:kappa: the threshold at which kappa is highest ("max kappa")spec_sens: the threshold at which the sum of the sensitivity (true positive rate) and specificity (true negative rate) is highestno_omission: the highest threshold at which there is no omissionprevalence: modeled prevalence is closest to observed prevalenceequal_sens_spec: equal sensitivity and specificitysensitivty: fixed (specified) sensitivity

See Also

evaluate

Examples

## See ?maxent for an example with real data.
# this is a contrived example:
# p has the predicted values for 50 known cases (locations)
# with presence of the phenomenon (species)
p <- rnorm(50, mean=0.7, sd=0.3)
# b has the predicted values for 50 background locations (or absence)
a <- rnorm(50, mean=0.4, sd=0.4)
e <- evaluate(p=p, a=a)

threshold(e)

Run the code above in your browser using DataCamp Workspace