R/get.R

In jsta/twilight: R interface to the USNO Sun or Moon Rise/Set Data Service

#' sunsetrise_yr
#' @importFrom rvest html_nodes html_text
#' @param year integer
#' @param lon_sign integer -1 for west
#' @param lon_deg integer degree
#' @param lon_min integer minute
#' @param lat_sign integer -1 for south
#' @param lat_deg integer degree
#' @param lat_min integer minute
#' @param tz integer timezone
#' @param tz_sign integer
#' @param state character two letter United States state abbreviation
#' @param city character
#' @export
#' @references \url{http://aa.usno.navy.mil/data/docs/RS_OneYear.php}
#' @return A 3 x 365 data.frame of sunrise, sunset, date where times are in GMT
#' @examples \dontrun{
#' sunsetrise_yr(year = 2015, lon_deg = 80, lon_min = 26, lat_deg = 25, lat_min = 5, tz = 5)
#'
#' sunsetrise_yr(year = 2015, state = "FL", city = "Key Largo")
#' }

sunsetrise_yr <- function(year, lon_sign = -1, lon_deg = NA, lon_min = NA,
                          lat_sign = 1, lat_deg = NA, lat_min = NA, tz = NA,
                          tz_sign = 1, state = NA, city = NA){

  url <- "http://aa.usno.navy.mil"

  is_place_query <- all(!is.na(c(state, city)))
  is_lonlat_query <- all(!is.na(
    c(lon_sign, lon_deg, lon_min, lat_sign, lat_deg, lat_min, tz, tz_sign)))

  if(!(is_place_query | is_lonlat_query)){
    stop("Must specify a complete set of either a state/city pair or
 geographic coordinate arguments.")
  }

  if(is_place_query & is_lonlat_query){
    stop("Must specify either a state/city or
 geographic coordinates but not both.")
  }

  if(is_place_query){
    query <-   list(
      ID = "JS",
      year = year,
      task = 0,
      state = state,
      place = city)
  }

  if(is_lonlat_query){
    query <-   list(
      ID = "JS",
      year = year,
      task = 0,
      lon_sign = lon_sign,
      lon_deg = lon_deg,
      lon_min = lon_min,
      lat_sign = lat_sign,
      lat_deg = lat_deg,
      lat_min = lat_min,
      tz = tz,
      tz_sign = tz_sign)
  }

  rs <- httr::GET(url, path = "cgi-bin/aa_rstablew.pl", query = query)

  rs <- rvest::html_nodes(
          xml2::read_html(
            httr::content(rs, "text")
        ), css = "pre")
  rs <- rvest::html_text(rs)
  rs <- strsplit(rs, "\n")

  header <- read_header(rs)
  body <- read_body(rs)

  # message(header)
  body
}