R/timeConv.R

In shirewoman2/LaurasHelpers: Miscellaneous Helper Functions for Common PK or Analytical Chemistry Tasks

#' Convert times from numbers to POSIXct
#'
#' Since data imported from Excel often changes date and time data to numeric,
#' \code{timeConv} converts dates from decimal numbers to Date with a time zone
#' of "UTC" unless otherwise specified.
#'
#' @param x A numeric string
#' @param dataSource dataSource Either "Excel" (default) or "Unix" depending on where
#'   the data are coming from. Excel data have an origin of Dec. 30, 1899
#'   whereas Unix or R data have an origin of Jan. 1, 1970.
#' @return Returns a POSIXct object
#'
#' @examples
#' timeConv(43252.5)
#' # "2018-06-01 12:00:00 UTC"
#'
#' timeConv(18526.2356, dataSource = "R")
#' # "2020-09-21 05:39:15 UTC"
#'
#' @export
#'

timeConv <- function(x, tz = "UTC", dataSource = "Excel") {

      if(dataSource %in% c("Excel", "Unix", "R") == FALSE){
            stop("Invalid selection for dataSource. Valid selections are 'Excel', 'Unix', or 'R'.")
      }

      output <-
            lubridate::ymd_hms(
                  format(
                        as.POSIXct(
                              as.Date(
                                    x,
                                    origin =
                                          ifelse(dataSource == "Excel",
                                                 "1899-12-30", "1970-01-01")),
                              tzone = tz), tz = tz))

      return(output)
}