geohash.py

import re
import pprint
import math

foo = """
field #0['loc']: [BinData(128, 611325C000000000), BinData(128, 611325FFFFFFFFFF)], [BinData(128, 6113274000000000), BinData(128, 6113277FFFFFFFFF)], [BinData(128, 611327C000000000), BinData(128, 611327FFFFFFFFFF)], [BinData(128, 61132D0000000000), BinData(128, 61132DFFFFFFFFFF)], [BinData(128, 61132F0000000000), BinData(128, 61132FFFFFFFFFFF)], [BinData(128, 6113300000000000), BinData(128, 611333FFFFFFFFFF)], [BinData(128, 6113340000000000), BinData(128, 611334FFFFFFFFFF)], [BinData(128, 6113360000000000), BinData(128, 611336FFFFFFFFFF)], [BinData(128, 6113380000000000), BinData(128, 61133BFFFFFFFFFF)], [BinData(128, 61133C0000000000), BinData(128, 61133CFFFFFFFFFF)], [BinData(128, 61133E0000000000), BinData(128, 61133EFFFFFFFFFF)], [BinData(128, 6113854000000000), BinData(128, 6113857FFFFFFFFF)], [BinData(128, 611385C000000000), BinData(128, 611385FFFFFFFFFF)], [BinData(128, 6113900000000000), BinData(128, 611390FFFFFFFFFF)], [BinData(128, 6113910000000000), BinData(128, 611391FFFFFFFFFF)], [BinData(128, 6113940000000000), BinData(128, 611394FFFFFFFFFF)]
"""

SCALING_FACTOR = 2 ** 32 / 360.0

## Initialized hashedToNormal array
hashedToNormal = [0] * 256
for i in range(16):
  fixed = 0
  for j in range(4):
      if (i & (i << j)) > 0:
          fixed |= 1 << (j * 2)
  hashedToNormal[fixed] = i

class HashBox(object):
  def __init__(self, min_point, max_point):
    super(HashBox, self).__init__()
    self.min_point = min_point
    self.max_point = max_point

def getHashes(s):
  hashes = []
  hashStrs = []
  for match in re.finditer('BinData\(128, ([0-9A-F]+)\)', s):
    hashStrs.append(match.group(1))

  for i in range(0, len(hashStrs), 2):
    start = int(hashStrs[i], 16)
    end = int(hashStrs[i+1], 16)
    level = get_bits(start, end)
    edge_size = 2.0 ** level / SCALING_FACTOR
    min_point = unhash_fast(start)
    max_point = { "x": min_point["x"] + edge_size, "y": min_point["y"]}
    hashes.append(HashBox(min_point, max_point))
  return hashes

# returns { x: Number, y: Number }
def unhash_fast(_hash):
  x = 0
  y = 0
  for i in range(8):
      c = _hash % 256
      _hash /= 256
      t = c & 0x55
      y |= hashedToNormal[t] << (4 * i)
      t = (c >> 1) & 0x55
      x |= hashedToNormal[t] << (4 * i)
  # scaling code
  x /= SCALING_FACTOR
  x -= 180
  y /= SCALING_FACTOR
  y -= 180
  return {'x': x, 'y': y}

def get_bits(start, end):
  bitHash = end - start;
  return int(math.log(bitHash, 2)) / 2

hash_boxes = getHashes(foo)

for box in hash_boxes:
  print box.min_point, box.max_point
# pprint.pprint(map(unhash_fast, hashes))