There are several methods to use free map services for visualizing a list of point-features. I found this wizard for instance at the gmaps samples. It uses a published Google Spreadsheets document and puts the listed features on a map. This method is a clever way because you can use Google Spreadsheets to hold, manage and edit your data and don’t have to go through the map publishing process over and over again when you update your data.
The problem with that wizard is, that you have to know the coordinates already. So it won’t help if there is just a list of addresses without coordinate information. You must geocode (assign coordinates to each address) your items before you can put them on a map with this method. And if the map should be shown somewhere else, you’ll need a Google Maps API key, which is tied to exactly one url-string.
Luckily Yahoo! invented the Pipes: I put a quick Pipe together which allows you to geocode addresses stored in a Google Spreadsheet.
Here is how it works:
- Enter a list of addresses in Google Spreadsheet. Here, for instance, is a list of shops in Vienna where you can grab a free copy of biber.
- The column “Name” identifies the name of my features and the column “Address” holds the address to geocode. If you want to use another structure, you should clone the pipe and adjust the Regex-module to match your needs.
- Publish your Google Spreadsheet as Atom or RSS feed (click the link “More publishing options” in the “Publish” section), e.g. the biber feed
- Enter the feed url into the “Google Spreadsheet feed url” field and hit “run pipe”
- A Yahoo! Map showing all your (successfully geocoded) addresses should be produced
Alternatively you can take the GeoRSS feed or KML-file from the Pipe and display it in Google Earth or put it on a Google Map (and embed it into a blog post).
Yahoo! Pipes are simple, yet powerful, and I think it should be possible to modify the Pipe in order to return a table containing coordinates. There is already a JSON output by default. Regarding the geocoding limit, I’m not sure which number applies for Yahoo! Pipes.