python: add support for __geo_interface__ - closes #2009

CHANGELOG.md

@@ -14,6 +14,8 @@ Released ...
 
 Summary: TODO
 
+- Python: added `__geo_interface__` to mapnik.Feature and mapnik.Path (#2009)
+
 - Python: Exposed optimized WKTReader for parsing WKT into geometry paths (6bfbb53)
 
 - Optimized expression evaluation of text by avoiding extra copy (1dd1275)

INSTALL.md

@@ -64,6 +64,7 @@ Mapnik Python bindings depend on:
 
  * Python 2.5-2.7 or >= 3.2 
  * Boost python
+ * simplejson module if using <= 2.5
 
 Note: Python 3.x is supported, see: https://github.com/mapnik/mapnik/wiki/Python3k
 

bindings/python/mapnik/__init__.py

@@ -43,6 +43,10 @@ import itertools
 import os
 import sys
 import warnings
+try:
+    import json
+except ImportError:
+    import simplejson as json
 
 def bootstrap_env():
     """
@@ -255,6 +259,12 @@ class _Projection(Projection,_injector):
         """
         return inverse_(obj,self)
 
+class _Feature(Feature,_injector):
+    __geo_interface__ = property(lambda self: json.loads(self.to_geojson()))
+
+class _Path(Path,_injector):
+    __geo_interface__ = property(lambda self: json.loads(self.to_geojson()))
+
 class _Datasource(Datasource,_injector):
 
     def all_features(self,fields=None):

tests/python_tests/feature_test.py

@@ -12,6 +12,12 @@ def test_default_constructor():
     f = mapnik.Feature(mapnik.Context(),1)
     eq_(f is not None,True)
 
+def test_feature_geo_interface():
+    ctx = mapnik.Context()
+    feat = mapnik.Feature(ctx,1)
+    feat.add_geometries_from_wkt('Point (0 0)')
+    eq_(feat.__geo_interface__['geometry'],{u'type': u'Point', u'coordinates': [0, 0]})
+
 def test_python_extended_constructor():
     context = mapnik.Context()
     context.push('foo')

tests/python_tests/geometry_io_test.py

@@ -79,6 +79,10 @@ geojson = [
 [1,'{"type":"Polygon","coordinates":[[[-178.32319,71.518365],[-178.321586,71.518439],[-178.259635,71.510688],[-178.304862,71.513129],[-178.32319,71.518365]],[[-178.32319,71.518365],[-178.341544,71.517524],[-178.32244,71.505439],[-178.215323,71.478034],[-178.193473,71.47663],[-178.147757,71.485175],[-178.124442,71.481879],[-178.005729,71.448615],[-178.017203,71.441413],[-178.054191,71.428778],[-178.047049,71.425727],[-178.033439,71.417792],[-178.026236,71.415107],[-178.030082,71.413459],[-178.039908,71.40766],[-177.970878,71.39643],[-177.779837,71.333197],[-177.718375,71.305243],[-177.706412,71.3039],[-177.68212,71.304877],[-177.670279,71.301825],[-177.655387,71.293158],[-177.587577,71.285956],[-177.548575,71.294867],[-177.531119,71.296332],[-177.51409,71.293402],[-177.498649,71.284735],[-177.506217,71.268622],[-177.486991,71.258734],[-177.459708,71.249884],[-177.443412,71.237006],[-177.445914,71.222663],[-177.457755,71.209357],[-177.507804,71.173774],[-177.581168,71.147589],[-177.637626,71.117011],[-177.684134,71.110968],[-177.751883,71.092963],[-177.819266,71.084662],[-177.877677,71.052558],[-177.930472,71.041449],[-178.206595,71.038398],[-178.310111,71.013617],[-178.875907,70.981024],[-178.980277,70.95069],[-179.342093,70.908026],[-179.336234,70.911078],[-179.322257,70.921698],[-179.364493,70.930243],[-179.457511,70.915534],[-179.501212,70.919684],[-179.666007,70.965461],[-179.853385,70.979438],[-179.888785,70.993598],[-179.907523,70.996772],[-179.999989,70.992011],[-179.999989,71.024848],[-179.999989,71.058661],[-179.999989,71.126166],[-179.999989,71.187018],[-179.999989,71.224189],[-179.999989,71.27497],[-179.999989,71.312079],[-179.999989,71.356024],[-179.999989,71.410041],[-179.999989,71.487799],[-179.999989,71.536689],[-179.862845,71.538642],[-179.912223,71.555854],[-179.900748,71.558478],[-179.798819,71.569098],[-179.757438,71.583197],[-179.735953,71.586432],[-179.715445,71.583258],[-179.697501,71.577338],[-179.678702,71.573676],[-179.610831,71.585211],[-179.372062,71.569098],[-179.326774,71.555487],[-179.306815,71.557563],[-179.287162,71.562934],[-179.24285,71.569098],[-179.204642,71.583197],[-179.074576,71.600043],[-178.395438,71.539008],[-178.32319,71.518365]]]}'],
 [2,'{"type":"MultiPolygon","coordinates":[[[[-178.32319,71.518365],[-178.321586,71.518439],[-178.259635,71.510688],[-178.304862,71.513129],[-178.32319,71.518365]]],[[[-178.32319,71.518365],[-178.341544,71.517524],[-178.32244,71.505439],[-178.215323,71.478034],[-178.193473,71.47663],[-178.147757,71.485175],[-178.124442,71.481879],[-178.005729,71.448615],[-178.017203,71.441413],[-178.054191,71.428778],[-178.047049,71.425727],[-178.033439,71.417792],[-178.026236,71.415107],[-178.030082,71.413459],[-178.039908,71.40766],[-177.970878,71.39643],[-177.779837,71.333197],[-177.718375,71.305243],[-177.706412,71.3039],[-177.68212,71.304877],[-177.670279,71.301825],[-177.655387,71.293158],[-177.587577,71.285956],[-177.548575,71.294867],[-177.531119,71.296332],[-177.51409,71.293402],[-177.498649,71.284735],[-177.506217,71.268622],[-177.486991,71.258734],[-177.459708,71.249884],[-177.443412,71.237006],[-177.445914,71.222663],[-177.457755,71.209357],[-177.507804,71.173774],[-177.581168,71.147589],[-177.637626,71.117011],[-177.684134,71.110968],[-177.751883,71.092963],[-177.819266,71.084662],[-177.877677,71.052558],[-177.930472,71.041449],[-178.206595,71.038398],[-178.310111,71.013617],[-178.875907,70.981024],[-178.980277,70.95069],[-179.342093,70.908026],[-179.336234,70.911078],[-179.322257,70.921698],[-179.364493,70.930243],[-179.457511,70.915534],[-179.501212,70.919684],[-179.666007,70.965461],[-179.853385,70.979438],[-179.888785,70.993598],[-179.907523,70.996772],[-179.999989,70.992011],[-179.999989,71.024848],[-179.999989,71.058661],[-179.999989,71.126166],[-179.999989,71.187018],[-179.999989,71.224189],[-179.999989,71.27497],[-179.999989,71.312079],[-179.999989,71.356024],[-179.999989,71.410041],[-179.999989,71.487799],[-179.999989,71.536689],[-179.862845,71.538642],[-179.912223,71.555854],[-179.900748,71.558478],[-179.798819,71.569098],[-179.757438,71.583197],[-179.735953,71.586432],[-179.715445,71.583258],[-179.697501,71.577338],[-179.678702,71.573676],[-179.610831,71.585211],[-179.372062,71.569098],[-179.326774,71.555487],[-179.306815,71.557563],[-179.287162,71.562934],[-179.24285,71.569098],[-179.204642,71.583197],[-179.074576,71.600043],[-178.395438,71.539008],[-178.32319,71.518365]]]]}']]
 
+def test_path_geo_interface():
+    path = mapnik.Path()
+    path.add_wkt('POINT(0 0)')
+    eq_(path.__geo_interface__,{u'type': u'Point', u'coordinates': [0, 0]})
 
 def test_wkb_parsing():
     path = mapnik.Path()