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Geohashing

Published on Thu, 22 May 2008

Geohashing xkcd comic

Randall Munroe proposed the awesomely geeky idea of geohashing via the xkcd comic and blag recently. The idea basically involves using the MD5 hash of a date combined with the opening value of the Dow Jones Index for that date to derive a latitude and longitude relative to a (generally your own) location.

However there is a problem for those of us residing in Australia (and other locations with a time zone significantly different from EST). With the Dow Jones Index operating on US time its not possible to determine a geohashed location in Australia until about 23:00 AEST for a given date. No doubt others have thought of this but I suggest we use the All Ordinaries Index instead. With that out of the way we just need some enterprising sole with some spare time to implement a version of the map based on this.

Update: More info on geohashing in Melbourne on the Visible Procrastinations blog.

Another Update: Using the Dow on the weekend works well though. As over the weekend everyone is more or less synced to the same index.

Final Update: The xkcd blag has a follow up article that clarifies the behaviour for Europe, Asia and Australia. It boils down to using the previous day’s Dow Jones Index.

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