R/getPMbyCityNames.R

In jinhuali/globalPM25: Query Real-Time Local Air Pollute PM2.5 Level

#' get real-timePM2.5 level at a city or a vector of cities
#'
#' @description Query real-time  PM2.5 levels measured by US EPA's AQI (Air Quality Index) and APL (Air Pollution Level) at a list of cities (default "san jose"). Return a tibble containing PM2.5 level, obervation station location, and local time. The results are sorted by PM2.5 AQI
#' @param citynames a vector of city names to be queryed
#' @return a tibble
#' @importFrom jsonlite fromJSON
#' @importFrom tibble tibble
#' @importFrom dplyr select arrange
#' @importFrom stats reorder
#' @importFrom ggplot2 geom_bar ggplot aes coord_flip scale_color_manual ggtitle
#' @export
#' @examples
#' \dontrun{getPMbyCityNames("san jose")} #require personal token
#' \dontrun{getPMbyCityNames(c("tokyo", "madrid"))}  
getPMbyCityNames <- function(uids){
  baseURL = getglobalPM25Options()$baseURL
  atoken = getglobalPM25Options()$token

  rslt <- list()
  for(uid in uids){
    mydata <- jsonlite::fromJSON(sprintf("%s/feed/@%s/?token=%s", baseURL, uid, atoken), flatten=TRUE)
    if(mydata$status!='ok'){
      next
    }
    arslt <- processPMdata(mydata)
    if(is.na(arslt[1][1])){
      next
    }
    print(sprintf("The air qaulity level at %s is %s", arslt$city, arslt$APL))
    rslt <- rbind(rslt, arslt)
  }

  rslt <- rslt %>%
    dplyr::select(stationid, city, localtime, APL, pm25, lat, lon, localtimezone) %>%
    dplyr::arrange(desc(pm25))
  dat <- tibble::as_tibble(rslt)

  if(length(uids) > 1){
    g <- ggplot2::ggplot(ggplot2::aes(x = reorder(city, pm25), y = pm25, fill=APL), data = dat) +
      ggplot2::geom_bar(stat = "identity") + ggplot2::scale_fill_manual(values = getglobalPM25Options()$apl_color[sort(unique(dat$APL))]) +
      ggplot2::coord_flip() +
      ggplot2::ggtitle(paste('Quertied at', Sys.time(), Sys.timezone(), sep = ' '))
    print(g)
  }

  dat
}