threshold_for_duration: Find threshold for given duration

In LightLogR: Process Data from Wearable Light Loggers and Optical Radiation Dosimeters

Find threshold for given duration

Description

This function finds the threshold for which light levels are above/below for a given duration. This function can be considered as the inverse of duration_above_threshold.

Usage

threshold_for_duration(
  Light.vector,
  Time.vector,
  duration,
  comparison = c("above", "below"),
  epoch = "dominant.epoch",
  na.rm = FALSE,
  as.df = FALSE
)

Arguments

Light.vector	Numeric vector containing the light data.
Time.vector	Vector containing the time data. Can be POSIXct, hms, duration, or difftime.
duration	The duration for which the threshold should be found. Can be either a duration or a string. If it is a string, it needs to be a valid duration string, e.g., "1 day" or "10 sec".
comparison	String specifying whether light levels above or below the threshold should be considered. Can be either "above" (the default) or "below".
epoch	The epoch at which the data was sampled. Can be either a duration or a string. If it is a string, it needs to be either "dominant.epoch" (the default) for a guess based on the data, or a valid duration string, e.g., "1 day" or "10 sec".
na.rm	Logical. Should missing values (NA) be removed for the calculation? Defaults to FALSE.
as.df	Logical. Should a data frame with be returned? If TRUE, a data frame with a single column named ⁠threshold_{comparison}_for_{duration}⁠ will be returned. Defaults to FALSE.

Value

Single numeric value or single column data frame.

See Also

Other metrics: bright_dark_period(), centroidLE(), disparity_index(), dose(), duration_above_threshold(), exponential_moving_average(), frequency_crossing_threshold(), interdaily_stability(), intradaily_variability(), midpointCE(), nvRC(), nvRD(), nvRD_cumulative_response(), period_above_threshold(), pulses_above_threshold(), timing_above_threshold()

Examples

N <- 60
# Dataset with 30 min < 250lx and 30min > 250lx
dataset1 <-
  tibble::tibble(
    Id = rep("A", N),
    Datetime = lubridate::as_datetime(0) + lubridate::minutes(1:N),
    MEDI = sample(c(sample(1:249, N / 2, replace = TRUE), 
                    sample(250:1000, N / 2, replace = TRUE))),
  )

dataset1 %>%
  dplyr::reframe("Threshold above which for 30 mins" = 
                   threshold_for_duration(MEDI, Datetime, duration = "30 mins"))

dataset1 %>%
  dplyr::reframe("Threshold below which for 30 mins" = 
                   threshold_for_duration(MEDI, Datetime, duration = "30 mins",
                                          comparison = "below"))

dataset1 %>%
  dplyr::reframe(threshold_for_duration(MEDI, Datetime, duration = "30 mins",
                                        as.df = TRUE))

LightLogR documentation built on June 10, 2025, 5:12 p.m.