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).

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

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

## Arguments

x Vector of x values. Vector of y values. 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")
#>  0.4980976area_under_curve(x, y, method = "step")
#>  0.4992463area_under_curve(x, y, method = "spline")
#>  0.4980982