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Plot the Chi-Square (Sokolove-Bushell) Periodogram

Source: R/circadian_plots.R
plot_chisq.Rd

Draws the chi-square periodogram from chi.sq.periodogram: the \(Q_P\) statistic against trial period, with the per-period chi-square significance threshold overlaid as a dashed line. The estimated period (the \(Q_P\) peak) is marked and a 24-hour reference line drawn. Unlike the Lomb-Scargle plot, the explicit threshold shows directly whether a rhythm is significant at a given period.

Usage

plot_chisq(
  counts,
  timestamps,
  from = 18,
  to = 30,
  alpha = 0.05,
  epoch_length = NULL
)

Arguments

counts

Numeric vector of activity counts on a regular epoch grid.

timestamps

A POSIXct vector the same length as counts.

from, to

Period search window in hours (default 18 to 30).

alpha

Significance level for the chi-square threshold (default 0.05).

epoch_length

Epoch length in seconds; inferred from timestamps when NULL.

Value

A ggplot object. Never errors; returns an annotated empty plot on insufficient data.

See also

plot_periodogram for the Lomb-Scargle spectrum.