[google-appengine] Re: Problems with Geohash / Inaccuracy / ow to deal with this ?

[Pierre VANNIER]

Pierre a écrit : Yep Adam, you're right. Turning into string seems to turn false to true. Good point but it doesn't solve my troubles completely. I try to copy paste some code and output to show you some weird things. Regards, Pierre On 4 sep, 19:31, Adam <[EMAIL PROTECTED]> wrote: Should you be using: str(hashPoi) > str(hashSW) or Geostring instead? A On Sep 4, 6:59 am, Pierre <[EMAIL PROTECTED]> wrote: Hi, Here's an example : [GCC 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2)] on linux2 Type "help", "copyright", "credits" or "license" for more information.>>> import geohash hashSW = geohash.Geohash((1.5765380859375,42.894076403348976)) hashNE = geohash.Geohash((6.1907958984375,44.3002644115815)) hashPoi = geohash.Geohash((3.867915,43.733638)) hashPoi > hashSW False hashPoi < hashNE True With geoIndex :>>> hashSW = geohash.Geoindex((1.5765380859375,42.894076403348976)) hashNE = geohash.Geoindex((6.1907958984375,44.3002644115815)) hashPoi = geohash.Geoindex((3.867915,43.733638)) hashPoi > hashSW False hashPoi < hashNE True I might be missing something but I thought : hash(SW) < hashPoi < hash(NE) How do you use it and do you find something different ? Regards, Pierre On 4 sep, 12:33, Ubaldo Huerta <[EMAIL PROTECTED]> wrote: Do you have a example of a point whose geohash value isn't greater than SW, NE geohashes? I've tried, in the python interpreter, many examples, and haven't observed what you're describing. It's pretty scary because I'm writing a lot of code for a geo app that's based on that property of geohashes, described athttp://labs.metacarta.com/blog/27.entry/, working. I knew about equator, etc cases needed special handling, but I'm not too concerned. -U On Sep 3, 10:23 pm, Pierre <[EMAIL PROTECTED]> wrote: Hi, I need to find points (lat/lng) within a certain bounding box. To do so, I tried Geohash python implementation (http://mappinghacks.com/ code/geohash.py.txt). Problem's data is : - I have 2 points (South west SW corner / North east NE corner) describing a geographic Bounding box - I have a model (let's call it 'Poi') having a field "geohash" of type Db.StringProperty + Lat and Lng field (Float) Question is : How on earth (lol :-) ) can I find all Poi within my bounding box ? I've already tried something like : Create Geohash for SW, create Geohash for NE and do something like : "SELECT * FROM Poi WHERE geohash >:1 and geohash <= :2, geohash(SW), geohash(NE)" Also tried with geoindex, at different depth but all this fails and still give points not located within Bounding box. Also tried like describe in "http://labs.metacarta.com/blog/27.entry/ geographic-queries-on-google-app-engine/" to create a small surrounding box for each Poi and then create a geohash for this specific bounding box to be in between my SW->NE bounding box.... Nothing is working even with "not worst case" (I mean equatorial problem...) case/ Any help will be greatly appreciated. Thanks all, Pierre Here is some code + corresponding output, you will see that it retrieves a point located outside bbox : geoHash1 = geohash.Geohash((float(point[1]), float(point[0]))) geoHash2 = geohash.Geohash((float(point[3]), float(point[2]))) logging.info(" SW : "+str(point[0])+" "+str(point[1])+"\n\t\t"+str(geoHash1)) logging.info(" NE : "+str(point[2])+" "+ str(point[3])+"\n\t\t"+str(geoHash2)) pois = db.GqlQuery("Select * from Poi WHERE geoHash >:1 and geoHash <:2",str(geoHash1),str(geoHash2)) pois1 = Poi.all() logging.info("Points already in the datastore : ") for poi in pois1:    logging.info(" Geohash poi "+poi.geoHash+" poiKey : "+str(poi.key())+" lat : "+str(poi.lat)+" Lng : "+str(poi.lng)+" ")    logging.info("-------------------------------------------------------") logging.info("Points for the given Bbox : ("+str(point[0])+","+str(point[1])+")->("+str(point[2])+" "+ str(point[3])+")") if pois.count() != 0:   for poi in pois:      logging.info(poi.geoHash+" poiKey : "+str(poi.key())+" lat : "+str(poi.lat)+" lng : "+str(poi.lng)) ************************************************************************************ And now, let's have a look at some output when draging map around and trying to see if point disapear both from screen and from query result when out of the (SW, NE) bbox : INFO:root: SW : 43.26720631662829 4.61151123046875                 speq0uw18pb50 INFO:root: NE : 44.18220395771566 8.12713623046875                 spvg2gn5bpb08 INFO:root:Points already in the datastore : INFO:root: Geohash poi spfb018s0yn6w poiKey : ag9hbmFseXRpY3NtYXNodXByCQsSA1BvaRgBDA lat : 43.602709 Lng : 3.867915 INFO:root:------------------------------------------------------- INFO:root:Points for the given Bbox : (43.26720631662829,4.61151123046875)->(44.18220395771566 8.12713623046875) INFO:root:spfb018s0yn6w poiKey : ag9hbmFseXRpY3NtYXNodXByCQsSA1BvaRgBDA lat : 43.602709 lng : 3.867915 ********************* Clearly : the unique point should be OUTSIDE the bbox thus not return in output "Points for the given Bbox". So, Am I doing something wrong either with datastore / GQL or geohash ? Thanks. Pierre --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appengine@googlegroups.com 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 -~----------~----~----~----~------~----~------~--~---