street address to geolocation lat/long

Question

I am considering rChart/LeafLet to create a shiny app for housing sales in my county. There are several hundred houses for sale at any given time. Want to map street address-to-geolocation (lat/long) for all and display them on a map. So, I am looking for a r package, service or database that can map street address to geolocation.

Fredette

nominatim : github.com/hrbrmstr/nominatim ; ggmap::geocode ; geocodeHERE::geocodeHERE_simple ; geonames package; also google r street address geolocation – Halette

Excelent article with code example (using package ggmap): shanelynn.ie/massive-geocoding-with-r-and-google-maps – Insist

Answer 1

Here is a function based on Harvey's suggestion. It will look for the address and give the coordinates of the first result. Have a look at the structure of x in the function to see other information you can get.

geocodeAdddress <- function(address) {
  require(RJSONIO)
  url <- "http://maps.google.com/maps/api/geocode/json?address="
  url <- URLencode(paste(url, address, "&sensor=false", sep = ""))
  x <- fromJSON(url, simplify = FALSE)
  if (x$status == "OK") {
    out <- c(x$results[[1]]$geometry$location$lng,
             x$results[[1]]$geometry$location$lat)
  } else {
    out <- NA
  }
  Sys.sleep(0.2)  # API only allows 5 requests per second
  out
}

For example:

R> geocodeAdddress("Time Square, New York City")
[1] -73.98722  40.7575

Viceregent

why are we building functions when packages exist for the exact same functionality? – Halette

@Halette I wasn't aware of that package, thanks for the heads up. – Viceregent

Can you share the package name choff? – Fredette

It's the one hrbrmstr mentioned in the comment on the question, nominatim. – Viceregent

Thanks @choff for the function! – Drying

Answer 2

I have used Google Geolocation, This is simple to set-up and easy to implement on almost any project:

https://developers.google.com/maps/documentation/geocoding/intro

Matriarchate

For future reference, this belongs in a comment, but I guess you don't have enough rep to do that so OK. – Naxos

Thanks Harvey. The goole maps limit the number of request to 10/sec or 2500 a day. Which is fine. is there a way to make a bulk request. Say I send 100 street addresses in and get 100 lon/lat back? – Fredette

Sorry I should have mentioned there was a limit. but for small applications its not much to worry about. I managed to perform multiple in an iOS app by simply looping requests. Although you may have to limit the speed of this due to multiple connections too fast may lock you out. Sorry I don't know the R specifics! – Matriarchate

Answer 3

Modified answer to account for the API requirement:

api_key <- c("YOUR_API_KEY")

geocodeAdddress <- function(address) {
  require(RJSONIO)
  url <- "https://maps.googleapis.com/maps/api/geocode/json?address="
  url <- URLencode(paste(url, address, sep = ""))
  url <- URLencode(paste(url, "&key=", api_key, sep = ""))
  x <- fromJSON(url, simplify = FALSE)
  print(x$status)
  if (x$status == "OK") {
    out <- c(x$results[[1]]$geometry$location$lng,
             x$results[[1]]$geometry$location$lat)
  } else {
    out <- NA
  }
  Sys.sleep(0.2)  # API only allows 5 requests per second
  out
}

Korella