R/guessDateFormat.R

In Sumpfohreule/MyUtilities: Collection of general functions which are useful in multiple contexts

#' Guess date format string
#'
#' Guesses the format string of a given date string for easier conversion to
#'  Date or POSIXct
#'
#' @param date.string A string containing a date
#' @export
#'
guessDateFormat <- function(date.string) {
  if (stringr::str_detect(date.string,
    pattern = "^[0-9]{4}-[0-9]{2}-[0-9]{2}.*$"
  )) {
    date.format <- "%Y-%m-%d"
  } else if (
    stringr::str_detect(
      string = date.string,
      pattern = "^[0-9]{2}\\.[0-9]{2}\\.[0-9]{4}.*$"
    )) {
    date.format <- "%d.%m.%Y"
  } else if (
    stringr::str_detect(
      string = date.string,
      pattern = "^[0-9]{1,2} [[:alpha:]]{3} [0-9]{4}.*$"
    )) {
    # TODO: make it work with different locals
    date.format <- "%d %b %Y"
  } else {
    stop("It was not possible to guess the date format")
  }
  if (
    stringr::str_detect(
      string = date.string,
      pattern = "[0-9]{2}:[0-9]{2}:[0-9]{2}$"
    )) {
    time.format <- "%H:%M:%S"
  } else if (
    stringr::str_detect(
      string = date.string,
      pattern = "[^:][0-9]{2}:[0-9]{2}$"
    )) {
    time.format <- "%H:%M"
  } else {
    time.format <- NULL
  }
  return(trimws(paste(date.format, time.format)))
}