Geocoding in R with Google Maps

user_159438 0
Viewed 17045

I've tried running the code to geocode locations in R via Google Maps and the XML package from this blog post: http://www.r-chart.com/2010/07/maps-geocoding-and-r-user-conference.html

Here are his functions:

getDocNodeVal=function(doc, path){
  sapply(getNodeSet(doc, path), function(el) xmlValue(el))
}

gGeoCode=function(str){
  library(XML)
  u=paste('http://maps.google.com/maps/api/geocode/xml?sensor=false&address=',str)
  doc = xmlTreeParse(u, useInternal=TRUE)
  str=gsub(' ','%20',str)
  lng=getDocNodeVal(doc, "/GeocodeResponse/result/geometry/location/lat")
  lat=getDocNodeVal(doc, "/GeocodeResponse/result/geometry/location/lng")
  c(lat,lng)
}

When I run gGeoCode(), I get the following error:

> gGeoCode("Philadelphia, PA")
failed to load external entity "http%3A//maps.google.com/maps/api/geocode/xml%3Fsensor=false&address=%20Philadelphia,%20PA"
Error: 1: failed to load external entity "http%3A//maps.google.com/maps/api/geocode/xml%3Fsensor=false&address=%20Philadelphia,%20PA"

If I just paste into a browser the API url with Philadelphia, PA appended to the end, like the string passed to xmlParseTree, I get a result that looks like legitimate xml when I download it.

Is this an issue with the code, or have I failed to configure something or another?

geocoding r google-maps
6 Answers

This code works using just the XML library

library(XML)
url = 'http://maps.googleapis.com/maps/api/geocode/xml?address=1600+Amphitheatre+Parkway,+Mountain+View,+CA&sensor=true'
doc = xmlTreeParse(url, useInternal=TRUE)
lat = as.numeric(xmlValue(getNodeSet(doc, '//location/lat')[[1]]))
lng = as.numeric(xmlValue(getNodeSet(doc, '//location/lng')[[1]]))
user_5739780
Related