R/8dr.R

In btupper/obpgtools: obpgtools for Ocean Biology Processing Group

#' Given a RasterStack or RasterBrick, convert the names to POSIXct dates
#'
#' @export
#' @param x RasterStack or RasterBrick with names like \code{A20150123}. It is
#'  an error to  provide a stack/brick without proper names.
#' @param form character  either 'Date' (default) or 'POSIXct'
#' @param tz the timezone, default \code{UTC}
#' @param time character defaults to \code{12:00:00}
#' @param fmt the format string to use
#' @return vector of Date or POSIXct dates
stack_dates = function(x, form = 'Date',
    tz = 'UTC', time = '12:00:00', fmt = 'A%Y%j %H:%M:%S'){
  if (!(inherits(x, 'RasterBrick') || inherits(x, 'RasterStack')))
      stop("input must be of class RasterBrick or RasterStack")
  switch(tolower(form[1]),
      'posixct' = try(as.POSIXct(paste(names(x), time), tz = tz, format = fmt)),
      try(as.Date(names(x), format = 'A%Y%j'))
      )
}

#' Given a RasterStack or RasterBrick list the days missing from the sequence.
#'
#' @export
#' @param x the RasterStack or RasterBrick
#' @param ... further arguments for \code{stack_dates()}
#' @return vector of zero or more Date or POSIXct dates missing
stack_missing_days = function(x, ...){
    d = stack_dates(x, ...)
    r = range(d)
    dd = seq(from = r[1], to = r[2], by = 'day')
    dd[!(dd %in% d)]
}