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# Geohash

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Geohash Brief Introduction...

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### Geohash

1. 1. Geohash {lat/lon → string} Python Developer Nepal Meetup #6 March 19, 2015
2. 2. Who am I? Narayan Kandel Developer at nLocate (Python/Django) Previously Java Developer at Deerwalk
3. 3. What I Will Cover 1. Our requirements 2. What is a geohash? 3. How does it work? 4. How we use it?
4. 4. Our Requirement ● Analyze visitor from different location ○ different data 1. business data 2. user generated log ● Duplication Check
5. 5. What is Geohashing Simple way to encode lat/lng into a string Compact string encoding of geographic coordinate with arbitrary precision Kathmandu - tuut, Chitwan - tuuj Invented by Gustavo Niemeyer for geohash.org Available in public domain http://en.wikipedia.org/wiki/geohash/
6. 6. Why do we need it when we have lat/lon Big address of venue ABC road Lalitpur Sub-Municipality -12, Kupondole Lalitpur, Bagmati Nepal Complicated Lat/Long {27.6830282799,85.3180309269}
7. 7. ● Subdivides space into "buckets" of grid shape ● Doesn't really represent a point, rather a bounding area in which the point is present ● Hierarchical spatial structure with gradual degradation ● Longer the geohash → Smaller the area snap taken from geohash.gofreerange.com
8. 8. How does it work?
9. 9. How does it work?
10. 10. Mapping 5 bits (25 ) = 32 alpha-numeric 1-9 b-z except a, i, l, o *http://en.wikipedia.org/wiki/Geohash
11. 11. How does it work?... demo snap taken from geohash.gofreerange.com
12. 12. Lets come to our problem ● Analyze visitor from different location Method 1: Polygon
13. 13. Analyze visitor from different location ... Method 2 Geohashing Prefix Matching
14. 14. Other Area Where we used it ● To find duplicate Spot - O(n2 )
15. 15. Other Application ● twitter - location based tweet count/find trend on particular location ● flickr/instagram - find location based photo with area selection on number of prefix ● alerter system at telecommunication (integration of hardware location + customer complain location) ● and many more...
16. 16. References ● Geohash - http://en.wikipedia.org/wiki/Geohash
17. 17. Thank You twitter: @dearnarayan email: narayan@nlocate.com