geohash_encode_decode
来源：互联网 发布：linux运维笔记 编辑：程序博客网 时间：2024/06/05 08:55
def goehash_encode(longitude, latitude, precision):
base32 = '0123456789bcdefghjkmnpqrstuvwxyz'
lon_interval, lat_interval = (-180.0,180.0), (-90.0, 90.0)
geohash = []
bits = [ 16, 8, 4, 2, 1 ]
bit = 0
ch = 0
even = True
while len(geohash) < precision:
if even:
mid = (lon_interval[0] + lon_interval[1]) /2
if longitude > mid:
ch |= bits[bit]
lon_interval = (mid, lon_interval[1])
else:
lon_interval = (lon_interval[0], mid)
else:
mid = (lat_interval[0] + lat_interval[1]) /2
if latitude > mid:
ch |= bits[bit]
lat_interval = (mid, lat_interval[1])
else:
lat_interval = (lat_interval[0], mid)
even = not even
if bit < 4:
bit += 1
else:
geohash += base32[ch]
bit = 0
ch = 0
return ''.join(geohash)
def goehash_decode(geohash):
base32 = '0123456789bcdefghjkmnpqrstuvwxyz'
decodemap = {}
for i in range(len(base32)):
decodemap[base32[i]] = i
del i
lon_interval, lat_interval = (-180.0,180.0), (-90.0, 90.0)
lat_err, lon_err = 90.0, 180.0
is_even = True
print decodemap
for c in geohash:
cd = decodemap[c]
for mask in [16, 8, 4, 2, 1]:
if is_even: # adds longitude info
lon_err /= 2
if cd & mask:
lon_interval = ((lon_interval[0]+lon_interval[1])/2, lon_interval[1])
else:
lon_interval = (lon_interval[0], (lon_interval[0]+lon_interval[1])/2)
else: # adds latitude info
lat_err /= 2
if cd & mask:
lat_interval = ((lat_interval[0]+lat_interval[1])/2, lat_interval[1])
else:
lat_interval = (lat_interval[0], (lat_interval[0]+lat_interval[1])/2)
is_even = not is_even
lat = (lat_interval[0] + lat_interval[1]) /2
lon = (lon_interval[0] + lon_interval[1]) /2
print lon_err, lat_err
return ','.join([str(lon), str(lat), str(lon_err), str(lat_err)])
print goehash_encode(109.22222601,34.01730767, 8)
print goehash_decode("wnrz4rjxt")
