gistfile1.py

class YandexEncoder(object):
    million = 10**6
    points = []
    alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_='
    def __init__(self, geom):
	#self._encode(geom)
	self.points = [
	    self.lift( (37.593578,55.735094) ),
	    self.lift( (37.592159,55.732469) ),
	    self.lift( (37.589374,55.734162) )
	]
	"""
	self.points = [
	    self.lift( (37.64,55.797924) ),
	    self.lift( (37.499924,55.699554) ),
	    self.lift( (37.843247,55.705758) )
	]
	"""
    def lift(self, t):
	return map(lambda w: int(self.million*w), t)

    def _encode(self, geom):
	if geom.geom_typeid == 0:
	    self.points.append( self.lift(geom.coords) )
	elif geom.geom_typeid in [1,2]:
	    for x in geom.coords:
		self.points.append( self.lift(x) )
	else:
	    for x in xrange(geom.num_geom):
		self._encode(geom[x])

    def toQWord(self, num):
	pholder = [0 for _ in range(0,32)]
	if num < 0: num += 4294967296
	i = 1
	while num > 0:
	    num, r = divmod(num, 2)
	    pholder[32-i] = r
	    i += 1
	return pholder

    def align(self, qword):
	return reduce(lambda a,c: c + a, [qword[i:i+8] for i in range(0,32,8)])

    def toAlignedQWord(self, num):
	return self.align(self.toQWord(num))

    def get_alpha(self, n):
	return self.alphabet[sum([d*(2**i) for i,d in enumerate(reversed(n))])]

    def encode(self):
	chunk_size = 6
	result = []
	encoded = []
	begin = (0,0)
	for x,y in self.points:
	    diffx, diffy = x - begin[0], y - begin[1]
	    encoded.extend(self.toAlignedQWord(diffx))
	    encoded.extend(self.toAlignedQWord(diffy))
	    begin = (x, y)
	i = 0
	while True:
	    chunk = encoded[i:i+chunk_size]
	    if len(chunk) < chunk_size:
		break
	    print i, ':', i+chunk_size, '-' , chunk, ' -> ', sum([d*(2**z) for z,d in enumerate(reversed(chunk))]), self.get_alpha(chunk)
	    result.append(self.get_alpha(chunk))
	    i += chunk_size
	diff = len(encoded) - i
	if diff > 0:
	    diff = diff / 2
	    for p in range(0,diff):
		result.append('=')
	return ''.join(result)