R/calculate_clockdrift.R

In KiranLDA/PAMLr: Suite Of Functions For Manipulating Pressure, Activity, Magnetism, Temperature And Light Data In R

#' Adjust time for clock drift
#'
#' Linearly rescale a sequence of dates to a new start and end time
#' to correct for clock drift in the tag.
#'
#' @title Clock Drift Adjustment
#' @param time a vector of POSIXct times.
#' @param start new start time as POSIXct.
#' @param end new end time as POSIXct.
#' @examples
#' dates = hoopoe$magnetic$date
#' drift = 12
#' adjusted_end = as.POSIXct(dplyr::last(hoopoe$magnetic$date) + 12*60, tz="UTC")
#' drift_corrected = calculate_clockdrift(time = dates,
#'                              start= dates[1],
#'                              end = adjusted_end)
#'
#' @importFrom stats approx
#'
#' @export
calculate_clockdrift <- function(time,
                       start,
                       end) {
  ntimes <- length(time)
  corrected_time <- .POSIXct(approx(time[c(1,ntimes)],c(start,end),time)$y)
  return(corrected_time)
}