ct_to_radian: Convert time to radians

In ct: Camera Trap Data Management and Multi-Method Ecological Analysis

Convert time to radians

Description

This function converts time values into radians, which is often used in circular statistics and time-of-day analyses.

Usage

ct_to_radian(data, times, format = "%H:%M:%S", time_zone = "UTC")

Arguments

data	A data frame containing a column with time values. Optional. If NULL, the times parameter is treated as a standalone vector.
times	A column name in the data or a vector of time values to be converted. Time values should be in a format recognized by as.POSIXct().
format	A string specifying the format of the time values, using the standard POSIX formatting syntax. Default is "%H:%M:%S".
time_zone	A string specifying the time zone for interpreting the time values. Default is "UTC".

Details

This function converts time values into radians based on a 24-hour clock:

• A full day (24 hours) corresponds to 2\pi radians.

• The fractional time of the day is calculated as:

  \text{Fraction of the day} = \frac{\text{hours}}{24} + \frac{\text{minutes}}{1440} + \frac{\text{seconds}}{86400}

For example, for a time of 23 hours, 6 minutes, and 12 seconds:

\text{Fraction of the day} = \frac{23}{24} + \frac{6}{1440} + \frac{12}{86400}

To convert this fraction into radians:

\text{Radians} = \text{Fraction of the day} \times 2\pi

Value

If data is provided, the function returns the input data frame with an additional column named time_radian. If data is not provided, the function returns a numeric vector of time values converted to radians.

Examples

# Convert a standalone vector of time values
times <- c("00:00:00", "06:00:00", "12:00:00", "18:00:00")
ct_to_radian(times = times, format = "%H:%M:%S")

# Convert a column of time values in a data frame
data <- data.frame(times = c("00:00:00", "06:00:00", "12:00:00", "18:00:00"))
ct_to_radian(data = data, times = times, format = "%H:%M:%S")

ct documentation built on Oct. 22, 2026, 1:07 a.m.