Add support for lon-lat/GeoJSON tuples

README.rst

@@ -35,6 +35,8 @@ This should return ``_p~iF~ps|U_ulL~ugC_hgN~eq`@``.
 
 You can set the required precision with the optional ``precision`` parameter. The default value is 5.
 
+You can encode lon-lat tuples by setting ``geojson=True``.
+
 Decoding
 --------
 
@@ -44,3 +46,5 @@ To get a set of coordinates represented by a given encoded polyline string::
     polyline.decode('u{~vFvyys@fS]')
 
 This should return ``[(40.63179, -8.65708), (40.62855, -8.65693)]``.
+
+You can decode into lon-lat tuples by setting ``geojson=True``.

polyline/__init__.py

@@ -3,28 +3,30 @@
 __version__ = '1.3.2'
 
 
-def decode(expression, precision=5):
+def decode(expression, precision=5, geojson=False):
     """
     Decode a polyline string into a set of coordinates.
 
     :param expression: Polyline string, e.g. 'u{~vFvyys@fS]'.
     :param precision: Precision of the encoded coordinates. Google Maps uses 5, OpenStreetMap uses 6.
         The default value is 5.
+    :param geojson: Set output of tuples to (lon, lat), as per https://tools.ietf.org/html/rfc7946#section-3.1.1
     :return: List of coordinate tuples
     """
-    return PolylineCodec().decode(expression, precision)
+    return PolylineCodec().decode(expression, precision, geojson)
 
 
-def encode(coordinates, precision=5):
+def encode(coordinates, precision=5, geojson=False):
     """
     Encode a set of coordinates in a polyline string.
 
     :param coordinates: List of coordinate tuples, e.g. [(0, 0), (1, 0)].
     :param precision: Precision of the coordinates to encode. Google Maps uses 5, OpenStreetMap uses 6.
         The default value is 5.
+    :param geojson: Set to True in order to encode lon-lat tuples.
     :return: The encoded polyline string.
     """
-    return PolylineCodec().encode(coordinates, precision)
+    return PolylineCodec().encode(coordinates, precision, geojson)
 
 
 __all__ = ['decode', 'encode']

polyline/codec.py

@@ -36,7 +36,7 @@ def _trans(self, value, index):
 
         return ~(result >> 1) if comp else (result >> 1), index
 
-    def decode(self, expression, precision=5):
+    def decode(self, expression, precision=5, geojson=False):
         coordinates, index, lat, lng, length, factor = [], 0, 0, 0, len(expression), float(10 ** precision)
 
         while index < length:
@@ -46,9 +46,15 @@ def decode(self, expression, precision=5):
             lng += lng_change
             coordinates.append((lat / factor, lng / factor))
 
+        if geojson is True:
+            coordinates = [t[::-1] for t in coordinates]
+
         return coordinates
 
-    def encode(self, coordinates, precision=5):
+    def encode(self, coordinates, precision=5, geojson=False):
+        if geojson is True:
+            coordinates = [t[::-1] for t in coordinates]
+
         output, factor = six.StringIO(), int(10 ** precision)
 
         self._write(output, coordinates[0][0], 0, factor)