Based on the DescTools AUC function. It can calculate the area under the curve with a naive algorithm or a more elaborated spline approach. The curve must be given by vectors of xy-coordinates. This function can handle unsorted x values (by sorting x) and ties for the x values (by ignoring duplicates).

## Usage

area_under_curve(x, y, method = c("trapezoid", "step", "spline"), ...)

auc(x, y, method = c("trapezoid", "step", "spline"), ...)

## Arguments

x

Vector of x values.

y

Vector of y values.

method

Method to compute the Area Under the Curve (AUC). Can be "trapezoid" (default), "step" or "spline". If "trapezoid", the curve is formed by connecting all points by a direct line (composite trapezoid rule). If "step" is chosen then a stepwise connection of two points is used. For calculating the area under a spline interpolation the splinefun function is used in combination with integrate.

...

Arguments passed to or from other methods.

DescTools

## Examples

library(bayestestR)
posterior <- distribution_normal(1000)

dens <- estimate_density(posterior)
dens <- dens[dens$x > 0, ] x <- dens$x
y <- dens\$y

area_under_curve(x, y, method = "trapezoid")
#> [1] 0.4980638
area_under_curve(x, y, method = "step")
#> [1] 0.4992903
area_under_curve(x, y, method = "spline")
#> [1] 0.4980639