Because of the way a geohash is created, chopping off charactors off the end reduces the percision of the 'point'
So a given geohash actually represents a box. The more charctors the smaller the box. And because you can do prefix searches on AppEngine, you can just store the location as a Geohash, and the query on that. limiting the length of the search string to define your box. It works, however the major issue is the boxes aren't symmetric or consistant, so defining a suitable prefix (or list of prefixes) is not trivial. http://docs.opengeo.org/geospiel/2009/01/22/b-tree-r-tree-we-all-tile-with-quad-tree/ On 02/05/2009, Andrew Badera <[email protected]> wrote: > How does geohash help one query a bounded box? Geohash is a single point. > > Thanks- > - Andy Badera > - [email protected] > - Google me: http://www.google.com/search?q=andrew+badera > > > > > On Sat, May 2, 2009 at 1:13 PM, Jim <[email protected]> wrote: > > > > Have you looked at the geohash approach? > > > > http://geohash.org/site/tips.html > > > > http://pypi.python.org/pypi/Geohash/1.0rc1 > > > > > > > > > > > > > > On May 1, 7:40 pm, Matt <[email protected]> wrote: > > > Hello, > > > > > > I'm building a simple mapping app that needs to be able to query for > > > all points inside a box of points. > > > > > > I noticed the mutiny library which has a technique for achieving this, > > > but it occurred to me to ask if there is perhaps a way to do it more > > > simply using GeoPtProperty properties. The mutiny approach is linked > > > below: > > > > > > > http://code.google.com/p/mutiny/source/browse/trunk/geobox.py > > > > > > Any advice on this would be much appreciated. > > > > > > > > > -- Barry - www.nearby.org.uk - www.geograph.org.uk - --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~----------~----~----~----~------~----~------~--~---
