I am right now very excited about the new Placemaker beta – a location extraction web service released at Where2.0. Using Placemaker you can find all the geographical locations in a feed or a text or a web url and you get them back as an array of places.
As a demo I took the Yahoo News feed and ran it through Placemaker. The resulting places are plotted on a map and the map moves from location to location when you hover over the news items.
The result is online at http://isithackday.com/hacks/placemaker/map.php

Getting the data from the data feed and running it through placemaker is very straight forward. I explained the basic principle in this blog post on the Yahoo Developer Network blog. The only thing to think about is to define the input and output types correctly:
If you look at the source of this example you will find that Placemaker injected contentlocation elements in the feed itself:
2514815
38.8913
-77.0337
23424793
21.511
-77.8068
23424977
48.8907
-116.982
55843872
19.9445
-75.1541
You’ll also notice that the elements are namespaced and the names of the locations in CDATA blocks, both things I hate with a passion. Not because they don’t make sense, but because simplexml can be drag to make understand them.
What I wanted to do with this data was twofold: create a JSON array of geo locations to plot on a map and a display of the news content. This is the PHP that does that:
$places = simplexml_load_string($results, 'SimpleXMLElement',
LIBXML_NOCDATA);
// if there are elements found
if($places->channel->item){
// start a JSON array
$output .= '[';
// start the HTML output
$html = '';
?>
The result of this can be seen here http://isithackday.com/hacks/placemaker/map-2.php.
The JavaScript to show the map is pretty straight forward and more or less the demo example of the maps API:
// will be called with the array assembled in PHP
function placeonmap(o){
// if there are locations
if(o.length > 0){
// create a new geopoints array to hold all locations
// this is needed to determine the original zoom
// level of the map
var geopoints = [];
// add map with controls
var map = new YMap(document.getElementById('map'));
map.addZoomLong();
map.addPanControl();
// loop over locations
for(var i=0;i);
That’s pretty much it. I am sure it can be refined, but it is amazing how easy it is to get geo information into any text with Placemaker.