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Simon Willnauer updated LUCENE-1815: ------------------------------------ Priority: Minor (was: Major) I don't think this shouldn't be major! > Geohash encode/decode floating point problems > --------------------------------------------- > > Key: LUCENE-1815 > URL: https://issues.apache.org/jira/browse/LUCENE-1815 > Project: Lucene - Java > Issue Type: Bug > Components: contrib/spatial > Affects Versions: 2.9 > Reporter: Wouter Heijke > Priority: Minor > > i'm finding the Geohash support in the spatial package to be rather > unreliable. > Here is the outcome of a test that encodes/decodes the same lat/lon and > geohash a few times. > the format: > action geohash=(latitude, longitude) > the result: > encode u173zq37x014=(52.3738007,4.8909347) > decode u173zq37x014=(52.373799999999996,4.890934) > encode u173zq37rpbw=(52.373799999999996,4.890934) > decode u173zq37rpbw=(52.373799999999996,4.8909329999999995) > encode u173zq37qzzy=(52.373799999999996,4.8909329999999995) > if I now change to the google code implementation: > encode u173zq37x014=(52.3738007,4.8909347) > decode u173zq37x014=(52.37380061298609,4.890934377908707) > encode u173zq37x014=(52.37380061298609,4.890934377908707) > decode u173zq37x014=(52.37380061298609,4.890934377908707) > encode u173zq37x014=(52.37380061298609,4.890934377908707) > Note the differences between the geohashes in both situations and the > lat/lon's! > Now things get worse if you work on low-precision geohashes: > decode u173=(52.0,4.0) > encode u14zg429yy84=(52.0,4.0) > decode u14zg429yy84=(52.0,3.999999) > encode u14zg429ywx6=(52.0,3.999999) > and google: > decode u173=(52.20703125,4.5703125) > encode u17300000000=(52.20703125,4.5703125) > decode u17300000000=(52.20703125,4.5703125) > encode u17300000000=(52.20703125,4.5703125) > We are using geohashes extensively and will now use the google code version > unfortunately. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online. --------------------------------------------------------------------- To unsubscribe, e-mail: java-dev-unsubscr...@lucene.apache.org For additional commands, e-mail: java-dev-h...@lucene.apache.org