诗酒趁年华_bc48

Geoprint is a geohash variant.

This algorithm is almost exactly identical to, and originally based
on, the Geohash module on Pypi by Leonard Norrgard, which in turn,
implements the geohash algorithm developed by Gustavo Niemeyer and
described in the wikipedia article:

http://en.wikipedia.org/wiki/Geohash

The main difference between this encoding and geohash is that it uses
a much smaller 'alphabet' of encoding characters to spell a hash,
instead of base32 encoding it uses simpler base4 encoding that uses
four possible states to encode each character instead of 32. This
results in longer, uglier, less compressed geohashes but they are more
useful for doing proximity searching using hash prefixes. Note that
like geohashes, there are edge cases near the equator and meridians
where points near each other have different prefixes.

All geoprints begin with either a 'w' or 'e' character to specify that
the hash belongs in the western or eastern hemisphere. The western
hemisphere includes all longitudes less than zero down to -180.0, and
the eastern hemisphere includes all longitudes greater than or equal
to zero, up to 180.0. Subsequent hash characters are one of g, a, t,
or c.

Geohash算法原理及实现

最近需要实现一个功能，查找车辆附近的加油站，如果车和加油站距离在200米以内，则查找成功。 加油站数量肯定不小，能否缩小查找范围，否则以遍历形式，效率肯定高不了。 Geoha...

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