R/QA2Char.R

In jianzhaobi/bjzresc: Jianzhao's Research-Related Functions

#' Convert Decimal to MAIAC Quality Flags
#'
#' Convert a decimal number to MAIAC quality flags
#'
#' @param num a decimal number less than or equal to 2^16 (since the QA flag only has 16 digits)
#'
#' @return An array of strings regarding the MAIAC QA flags
#'
#' @examples
#' QA2Char(8)
#' @export

QA2Char <- function(num) {

  if (!is.na(num)) {
    # Decimal to binary
    char <- paste(sapply(strsplit(paste(rev(intToBits(num))),""),`[[`,2),collapse="")
    # Extract the last 16 digits
    char <- substr(char, 17, 32)

    # QA array
    qa.arr <- c(substr(char, 1, 1), # 15 Reserved
                substr(char, 2, 3), # 13-14 Aerosol Model
                substr(char, 4, 4), # 12 Glint Mask
                substr(char, 5, 8), # 8-11 QA AOD
                substr(char, 9, 11), # 5-7 Ajacency Mask
                substr(char, 12, 13), # 3-4 Land Water Snow/Ice Mask
                substr(char, 14, 16)) # 0-2 Cloud Mask
  } else {
    qa.arr <- rep(NA, 7)
  }

  return(qa.arr)
}