powerBI-importWeather.R

library(checkpoint)
checkpoint("2016-04-22")

library(weatherData)

city <- "SJC"
cityLongName <- "San Jose"
yearStart <- 1991
yearEnd <- 2015

## check for an existing cached data file
cacheDir <- "c:/Users/davidsmi/Downloads/WeatherData"
filebase <- paste(city, yearStart, yearEnd, sep = "-")
filename <- paste(cacheDir, "/", filebase, ".Rd", sep = "")
if (file.exists(filename)) {
    load(filename)
} else {
    ## download data from Weather Underground
        if (!checkDataAvailability(city, paste(yearStart, "-01-01", sep = ""))
            || !checkDataAvailability(city, paste(yearEnd, "-12-31", sep = ""))) {
        stop("Data not available for selected city/dates")
    }

    weatherHistory <- NULL
    for (year in yearStart:yearEnd) {
        weatherHistory <- rbind(weatherHistory,
                      getWeatherForYear(city, year))
    }
    

    weatherHistory$Date <- as.Date(weatherHistory$Date)
    weatherHistory$Year <- as.numeric(format(weatherHistory$Date, "%Y"))
    weatherHistory$City <- rep(cityLongName, nrow(weatherHistory))

    attr(weatherHistory, "CityName") <- city
    attr(weatherHistory, "CityLongName") <- cityLongName
    
    
    save("weatherHistory", file=filename)
}

assign(paste(city, "weather", sep = ""), weatherHistory)
rm("weatherHistory")