get weather data from wunderground

weather.R

getweather <- function() {
  library(RCurl)
  library(RJSONIO)
  library(XML)
  # 输入需要查询的城市名称，若中国城市则输入拼音即可，如：beijin
  city <- as.character(readline('please input the city name：'))
  # 从google API处获得经纬度数据
  requestUrl<-paste("http://maps.googleapis.com/maps/api/geocode
    /xml?address=",city,"&sensor=false", sep="")
  xmlResult<-xmlTreeParse(requestUrl,isURL=TRUE)
  root <- xmlRoot(xmlResult)
  lat <-xmlValue(root[['result']][['geometry']][['location']][['lat']])
  lon <-xmlValue(root[['result']][['geometry']][['location']][['lng']])
  # 将经纬度数据输入到wunderground.com的API中获得天气数据
  # 注意你要申请自己的key放到your_key处
  url <- 'http://api.wunderground.com/api/your_key/conditions/
    forecast/lang:CN/q/'
  finalurl <- paste(url,as.character(lat),',',as.character(lon),
    '.json',sep='')
  web <- getURL(finalurl)
  raw <-fromJSON(web)
  high <- raw$forecast$simpleforecast$forecastday[[2]]$high['celsius']
  low <- raw$forecast$simpleforecast$forecastday[[2]]$low['celsius']
  condition <- raw$forecast$simpleforecast$forecastday[[2]]$conditions
  currenttemp <- raw$current_observation$temp_c
  currentweather <- raw$current_observation$weather
  result <-list(current=paste(currenttemp,'°C ',currentweather,sep=''),
    tomorrow=paste(high,'°C','-',low,'°C ',condition,sep=''))
  names(result) <-c('当前', '明天')
  return(result)
}

very helpful! THs!