Fix #4 and #14.

Compatibility with Python 3.
Update Readme.

README.md

@@ -14,7 +14,7 @@ Converts a lat,lon to pixel space to tile space to a quadkey
     import quadkey
 
     qk = quadkey.from_geo((-105, 40), 17)
-    print qk.key # => 02310101232121212 
+    print(qk.key) # => 02310101232121212 
     assert qk.level is 17
     tile = qk.to_tile() # => [(x, y), z]
 
@@ -24,7 +24,7 @@ Not a lot of documentation here, but the implementation has quite a bit, so look
 Install
 -------
 
-The package on pypi is quadtweet, so the recommended installation is with pip
+The package on PyPI is quadkey, so the recommended installation is with pip
 
      pip install quadkey
 
@@ -38,16 +38,19 @@ There are many straightforward methods, so I'll only go into detail of the uniqu
 * is_ancestor()
 * is_descendent()
 * area()
+* side()
+* nearby()
 * to_geo()
 * to_tile()
+* to_pixel()
 
-####difference(to)
+#### difference(to)
 
 Gets the quadkeys between self and to forming a rectangle, inclusive.
 
     qk.difference(to) -> [qk,,,,,to]
 
-####unwind()
+#### unwind()
 
 Gets a list of all ancestors in descending order by level, inclusive.
 

quadkey/__init__.py

@@ -1,5 +1,5 @@
-from util import precondition
-from tile_system import TileSystem, valid_key
+from .util import precondition
+from .tile_system import TileSystem, valid_key
 
 LAT_STR = 'lat'
 LON_STR = 'lon'
@@ -27,7 +27,7 @@ def nearby(self):
         perms = [(-1, -1), (-1, 0), (-1, 1), (0, -1),
                  (0, 1), (1, -1), (1, 0), (1, 1)]
         tiles = set(
-            map(lambda perm: (abs(tile[0] + perm[0]), abs(tile[1] + perm[1])), perms))
+            [(abs(tile[0] + perm[0]), abs(tile[1] + perm[1])) for perm in perms])
         return [TileSystem.tile_to_quadkey(tile, level) for tile in tiles]
 
     def is_ancestor(self, node):
@@ -48,44 +48,50 @@ def is_descendent(self, node):
         """
         return node.is_ancestor(self)
 
+    def side(self):
+        return 256 * TileSystem.ground_resolution(0, self.level)
+
     def area(self):
-        size = TileSystem.map_size(self.level)
-        LAT = 0
-        res = TileSystem.ground_resolution(LAT, self.level)
-        side = (size / 2) * res
+        side = self.side()
         return side * side
 
-    def xdifference(self, to):
+    @staticmethod
+    def xdifference(first, second):
         """ Generator
             Gives the difference of quadkeys between self and to
             Generator in case done on a low level
             Only works with quadkeys of same level
         """
-        x,y = 0,1
-        assert self.level == to.level
-        self_tile = list(self.to_tile()[0])
-        to_tile = list(to.to_tile()[0])
-        if self_tile[x] >= to_tile[x] and self_tile[y] <= self_tile[y]:
-            ne_tile, sw_tile = self_tile, to_tile
-        else:
-            sw_tile, ne_tile = self_tile, to_tile
-        cur = ne_tile[:]
-        while cur[x] >= sw_tile[x]:
-            while cur[y] <= sw_tile[y]:
-                yield from_tile(tuple(cur), self.level)
-                cur[y] += 1
+        x, y = 0, 1
+        assert first.level == second.level
+        self_tile = list(first.to_tile()[0])
+        to_tile = list(second.to_tile()[0])
+        se, sw, ne, nw = None, None, None, None
+        if self_tile[x] >= to_tile[x] and self_tile[y] <= to_tile[y]:
+            ne, sw = self_tile, to_tile
+        elif self_tile[x] <= to_tile[x] and self_tile[y] >= to_tile[y]:
+            sw, ne = self_tile, to_tile
+        elif self_tile[x] <= to_tile[x] and self_tile[y] <= to_tile[y]:
+            nw, se = self_tile, to_tile
+        elif self_tile[x] >= to_tile[x] and self_tile[y] >= to_tile[y]:
+            se, nw = self_tile, to_tile
+        cur = ne[:] if ne else se[:]
+        while cur[x] >= (sw[x] if sw else nw[x]):
+            while (sw and cur[y] <= sw[y]) or (nw and cur[y] >= nw[y]):
+                yield from_tile(tuple(cur), first.level)
+                cur[y] += 1 if sw else -1
             cur[x] -= 1
-            cur[y] = ne_tile[y]
+            cur[y] = ne[y] if ne else se[y]
 
     def difference(self, to):
         """ Non generator version of xdifference
         """
-        return [qk for qk in self.xdifference(to)]
+        return [qk for qk in self.xdifference(self, to)]
 
     def unwind(self):
         """ Get a list of all ancestors in descending order of level, including a new instance  of self
         """
-        return [ QuadKey(self.key[:l+1]) for l in reversed(range(len(self.key))) ]
+        return [ QuadKey(self.key[:l+1]) for l in reversed(list(range(len(self.key)))) ]
 
     def to_tile(self):
         return TileSystem.quadkey_to_tile(self.key)
@@ -98,11 +104,14 @@ def to_geo(self, centered=False):
         return TileSystem.pixel_to_geo(pixel, lvl)
 
     def __eq__(self, other):
-        return self.key == other.key
+        return isinstance(other, QuadKey) and self.key == other.key
 
     def __ne__(self, other):
         return not self.__eq__(other)
 
+    def __lt__(self, other):
+        return self.key.__lt__(other.key)
+
     def __str__(self):
         return self.key
 

quadkey/tile_system.py

@@ -1,4 +1,4 @@
-from util import precondition
+from .util import precondition
 from math import sin, cos, atan, exp, log, pi
 
 
@@ -84,7 +84,7 @@ def pixel_to_geo(pixel, level):
     @staticmethod
     def pixel_to_tile(pixel):
         """Transform pixel to tile coordinates"""
-        return pixel[0] / 256, pixel[1] / 256
+        return int(pixel[0] / 256), int(pixel[1] / 256)
 
     @staticmethod
     def tile_to_pixel(tile, centered=False):
@@ -99,10 +99,10 @@ def tile_to_pixel(tile, centered=False):
     @precondition(lambda tile, lvl: valid_level(lvl))
     def tile_to_quadkey(tile, level):
         """Transform tile coordinates to a quadkey"""
-        tile_x = tile[0]
-        tile_y = tile[1]
+        tile_x = int(tile[0])
+        tile_y = int(tile[1])
         quadkey = ""
-        for i in xrange(level):
+        for i in range(level):
             bit = level - i
             digit = ord('0')
             mask = 1 << (bit - 1)  # if (bit - 1) > 0 else 1 >> (bit - 1)
@@ -118,7 +118,7 @@ def quadkey_to_tile(quadkey):
         """Transform quadkey to tile coordinates"""
         tile_x, tile_y = (0, 0)
         level = len(quadkey)
-        for i in xrange(level):
+        for i in range(level):
             bit = level - i
             mask = 1 << (bit - 1)
             if quadkey[level - bit] == '1':

tests/quadkey_tests.py

@@ -28,7 +28,7 @@ def testChildren(self):
         qk = quadkey.from_str('0')
         self.assertEqual(
             [c.key for c in qk.children()], ['00', '01', '02', '03'])
-        qk = quadkey.from_str(''.join(['0' for x in xrange(23)]))
+        qk = quadkey.from_str(''.join(['0' for x in range(23)]))
         self.assertEqual(qk.children(), [])
 
     def testAncestry(self):
@@ -61,5 +61,22 @@ def testDifference(self):
         self.assertEqual(diff, set([qk.key for qk in _to.difference(_from)]))
         self.assertEqual(diff, set([qk.key for qk in _from.difference(_to)]))
 
+    def testDifference2(self):
+        qk1 = quadkey.QuadKey('033')
+        qk2 = quadkey.QuadKey('003')
+        diff = [qk.key for qk in qk1.difference(qk2)]
+        self.assertEqual(set(diff), set(['033', '031', '013', '032', '030', '012', '023', '021', '003']))
 
+    def testDifference3(self):
+        qk1 = quadkey.QuadKey('021')
+        qk2 = quadkey.QuadKey('011')
+        diff = [qk.key for qk in qk1.difference(qk2)]
+        self.assertEqual(set(diff), set(['011', '013', '031', '010', '012', '030', '001', '003', '021']))
 
+    def testSide(self):
+        qk = quadkey.QuadKey(''.join(['0'] * 10))
+        self.assertEqual(int(qk.side()), 39135)
+
+    def testArea(self):
+        qk = quadkey.QuadKey(''.join(['0'] * 10))
+        self.assertEqual(int(qk.area()), 1531607591)

tests/tile_system.py

@@ -26,7 +26,7 @@ def testMapScale(self):
         geo = (40., -105.)
         level = 7
         dpi = 96
-        scale = 3540913.0290224836
+        scale = 3540913.029022482
         self.assertEqual(scale, TileSystem.map_scale(geo[0], level, dpi))
 
     def testGeoToPixel(self):