R/getPlace.R

In icejean/gaodemap: A package for spatial visualization with GaoDe map

#' Transform the query character to raw character
#' Take in query and city, return the informations
#' @param a character
#' @return raw character with %. It's used in getPlace.
#' @examples 
#' 
#' \dontrun{
#' url_character('北京')
#' # "%e5%8c%97%e4%ba%ac"
#' }
url_character = function(x){
  #raw = as.character(charToRaw(x))
  #paste0('%', raw, collapse='')
  if(length(x)==1)
    x<-URLencode(iconv(x,"GBK","UTF-8"))
  else{
    for(i in 1:length(x))
      x[i]<-URLencode(iconv(x[i],"GBK","UTF-8"))
  }
  return(x)
}

#' Get place from query
#' Take in query and city, return the informations
#' @param place the place you want to search
#' @param city define the city
#' @return a data frame contains name, longtitude, latitude and address, as well as teleplhone number, if exist.
#' @export getPlace
#' @importFrom RCurl getURL
#' @importFrom rjson fromJSON
#' @examples
#' \dontrun{
#' ## colleges in beijing
#' bj_college = getPlace('大学', '北京')
#' ## Mcdonald's in shanghai
#' sh_mcdonald = getPlace('麦当劳', '上海')
#' }
getPlace = function(place=NULL, city='北京', page_size=20, 
                    pages=Inf, extensions="base", verbose=TRUE, map_ak=''){
  if (map_ak == '' && is.null(getOption('gaode.key'))){
    stop(Notification)
  }else{
    map_ak = ifelse(map_ak == '', getOption('gaode.key'), map_ak)
  }
  ### character
  place = url_character(place)
  city = url_character(city)
  
  ### url
  url_head = 'https://restapi.amap.com/v3/place/text?key='
  url = function(page) {
    sprintf('%s%s&output=json&keywords=%s&offset=%s&page=%s&extensions=%s&city=%s',
            url_head, map_ak, place, page_size, page, extensions, city)
  }
  
  ### formate the result   
  formate = function(x){
    info = sapply(x, function(y) c(ifelse(is.null(y$name), NA, y$name),
                                   ifelse(is.null(y$address), NA, y$address),
                                   ifelse(is.null(y$location), NA, y$location),
                                   ifelse(is.null(y$tel), NA, y$tel)))
    info = as.data.frame(t(info), stringsAsFactors = FALSE)
    if (nrow(info) > 0 & ncol(info) > 0) {
      colnames(info) = c('name', 'address', 'location', 'telephone')
      coor<-t(as.data.frame(str_split(info$location,",")))
      info$lon<-coor[,1]
      info$lat<-coor[,2]
      info$location<-NULL
      info<-info[,c(1,2,4,5,3)]
    }
    return(info)
  }
  
  ### get result
  getResult = function(page_num = 0){
    url<-url(page_num)
    #cat(url);cat("\n")
    result <<- getURL(url, .encoding = 'UTF8')
    result = fromJSON(result)
    total = as.numeric(result$count)
    pois = result$pois
    result_formate = formate(pois)
    return(list(total = total, result = result_formate))
  }
  
  ### start to scraping
  result = getResult(1)
  address = result$result
  total_page = min(ceiling(result$total / 20), pages)
  if (verbose) {
    cat('Get',  result$total, 'records,', total_page, 'page.', '\n')
    cat('    Getting ', 1, 'th page', '\n')
  }
  if (total_page > 1){
    for (i in 2:total_page){
      if (verbose) cat('    Getting ', i, 'th page', '\n')
      address_i = getResult(i)$result
      address = rbind(address, address_i)
      if (nrow(address_i) < 20) break;
    }
    cat('Done!', '\n')
  }
  
  address$lat = as.numeric(address$lat)
  address$lon = as.numeric(address$lon)
  address$name<-as.character(address$name)
  address$address<-as.character(address$address)
  address$telephone<-as.character(address$telephone)
  
  return(address)
}