Hjorth Mobility and Complexity — hjorth

Computes the Hjorth parameters (Hjorth 1970): mobility, a proxy for mean frequency derived from the variance ratio of the first difference to the signal itself; and complexity, a proxy for bandwidth/irregularity derived from the second difference. Ported from Lucas Franca's own mrpheus package (AASM staging feature pipeline). Uses Bessel-corrected (ddof = 1) variance throughout, deliberately matching R's var() convention – this was mrpheus's original design choice, and differs slightly from the antropy Python library's population-variance (ddof = 0) convention. The two converge as length(x) grows but differ meaningfully for short series; see inst/COPYRIGHTS.

Usage

hjorth_parameters(x)

Arguments

x: Numeric vector. The time series to analyse.

Value

A named list with mobility and complexity.

References

Hjorth B. EEG analysis based on time domain properties. Electroencephalogr Clin Neurophysiol 1970;29(3):306-310.

Examples

set.seed(1)
hjorth_parameters(rnorm(1000))
#> $mobility
#> [1] 1.441764
#> 
#> $complexity
#> [1] 1.203156
#>