R/dates.R

In r4ecology/rcdo: Tools to manipulate netcdf data

#' @title Find dates in a netcdf file
#'
#' @description Find dates in a netcdf file
#' @param ff This is the file to read dates from.
#' @export

# need an option for cacheing results...

#' @examples
#' 
#' # Get the dates in the sample file
#' ff <- system.file("extdata", "woa18_decav_t01_01.nc", package = "rcdo")
#' nc_dates(ff)
nc_dates <- function(ff) {
  if (!file_valid(ff)) {
    stop(stringr::str_glue("error: {ff} does not exist or is not netcdf"))
  }

  ff_dates <<- system(stringr::str_c("cdo showtimestamp ", ff), intern = TRUE, ignore.stderr = TRUE) %>%
    stringr::str_split(" ") %>%
    .[[1]]
  ff_dates <- ff_dates[ff_dates != ""]
  ff_dates <- as.Date(ff_dates)
  dplyr::data_frame(Date = ff_dates) %>%
    dplyr::distinct() %>%
    dplyr::mutate(Year = lubridate::year(Date)) %>%
    dplyr::mutate(Month = lubridate::month(Date)) %>%
    dplyr::mutate(Day = lubridate::day(Date))
}