Define Intermediate Segment of Melatonin Profile

This function identifies and labels the intermediate segment of a melatonin profile. The intermediate segment lies between the base segment and the ascending segment, where melatonin concentrations begin to rise but have not crossed the threshold value.

Usage

define_intermediate_segment(profile_data, threshold = 2.3)

Arguments

profile_data

A tibble containing the melatonin profile with the following columns:

• datetime: A POSIXct column representing timestamps for each measurement.

• melatonin: Numeric column representing melatonin concentrations.

• base: Binary column (1 for base segment, 0 otherwise).

• ascending: Binary column (1 for ascending segment, 0 otherwise).

threshold

Numeric. The melatonin concentration threshold for defining profile segments (default = 2.3 pg/mL).

Value

A tibble with an additional intermediate column:

• intermediate: Binary column (1 for intermediate segment, 0 otherwise).

If no intermediate segment is identified, the intermediate column will not be created.

Examples

library(dplyr)
library(lubridate)

# Example data
profile_data <- tibble(
  datetime = seq(ymd_hms("2023-01-01 20:00:00"), by = "15 min", length.out = 12),
  melatonin = c(1.2, 1.4, 1.5, 2.0, 2.5, 2.3, 2.8, 3.5, 4.2, 4.7, 5.0, 5.2),
  base = c(1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0),
  ascending = c(0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1)
)

# Define the intermediate segment
updated_profile <- define_intermediate_segment(profile_data, threshold = 2.3)
#> Warning: Unknown or uninitialised column: `slope`.
#> Error in if (is.na(last_base_row) & is.na(profile_data$slope[1])) {    profile_data$base[1] <- 1    last_base_row <- 1}: argument is of length zero
print(updated_profile)
#> Error: object 'updated_profile' not found