lomb_scargle_periodogram {digiRhythm}

Computes the Lomb Scargle Periodogram and returns the information needed for computing the DFC and HP. A plot visualizing the Harmonic Frequencies presence in the spectrum is possible. The function is inspired from the Lomb library in a great part, with modifications to fit the requirements of harmonic powers and computation of the DFC. This function is inspired by the lsp function from the lomb package and adapted to add different colors for harmonic and non harmonic frequencies in the signal. For more information about lomb::lsp, please refer to: https://cran.r-project.org/web/packages/lomb/

Description

Computes the Lomb Scargle Periodogram and returns the information needed for computing the DFC and HP. A plot visualizing the Harmonic Frequencies presence in the spectrum is possible. The function is inspired from the Lomb library in a great part, with modifications to fit the requirements of harmonic powers and computation of the DFC. This function is inspired by the lsp function from the lomb package and adapted to add different colors for harmonic and non harmonic frequencies in the signal. For more information about lomb::lsp, please refer to: https://cran.r-project.org/web/packages/lomb/

Usage

lomb_scargle_periodogram(
  data,
  alpha = 0.01,
  harm_cutoff = 12,
  sampling = 15,
  plot = TRUE,
  extra_info_plot = TRUE
)

Arguments

data

a digiRhythm friendly dataframe of only two columns

alpha

the statistical significance for the false alarm

harm_cutoff

the order of the highest harmonic needed to be considered. An integer equal to 1, 2, 3, ... Default is 12.

sampling

the sampling period in minutes. default = 15 min.

plot

if TRUE, the LSP will be plotted

extra_info_plot

if True, extra information will be shown on the plot

Value

a list that contains a dataframe (detailed below), the significance level and significance (for the record). The dataframe contains the power the frequency, the frequency in HZ, the p values according to Baluev 2008, the period that corresponds to the frequency in seconds and in hours and finally, a boolean to tell whether the frequency is harmonic or not.

Examples

data("df516b_2", package = "digiRhythm")
data <- df516b_2[1:672, c(1, 2)]
lomb_scargle_periodogram(data, alpha = 0.01, harm_cutof = 12, plot = TRUE)