Merge pull request #55 from geopandas/feature/coordinate_index

Add coordinate indexing

geopandas/geoseries.py

@@ -3,8 +3,10 @@ from warnings import warn
 
 import numpy as np
 from pandas import Series, DataFrame
+from pandas.core.indexing import _NDFrameIndexer
+from pandas.util.decorators import cache_readonly
 import pyproj
-from shapely.geometry import shape, Polygon, Point
+from shapely.geometry import box, shape, Polygon, Point
 from shapely.geometry.collection import GeometryCollection
 from shapely.geometry.base import BaseGeometry
 from shapely.ops import transform
@@ -25,6 +27,28 @@ def _convert_array_args(args):
         args = ([args[0]],)
     return args
 
+class _CoordinateIndexer(_NDFrameIndexer):
+    """ Indexing by coordinate slices """
+    def _getitem_tuple(self, tup):
+        obj = self.obj
+        xs, ys = tup
+        # handle numeric values as x and/or y coordinate index
+        if type(xs) is not slice:
+            xs = slice(xs, xs)
+        if type(ys) is not slice:
+            ys = slice(ys, ys)
+        # don't know how to handle step; should this raise?
+        if xs.step is not None or ys.step is not None:
+            warn("Ignoring step - full interval is used.")
+        xmin, ymin, xmax, ymax = obj.total_bounds
+        bbox = box(xs.start or xmin,
+                   ys.start or ymin,
+                   xs.stop or xmax,
+                   ys.stop or ymax)
+        idx = obj.intersects(bbox)
+        return obj[idx]
+
+
 class GeoSeries(GeoPandasBase, Series):
     """A Series object designed to store shapely geometry objects."""
     _metadata = ['name', 'crs']
@@ -262,3 +286,5 @@ class GeoSeries(GeoPandasBase, Series):
     def __sub__(self, other):
         """Implement - operator as for builtin set type"""
         return self.difference(other)
+
+GeoSeries._create_indexer('cx', _CoordinateIndexer)

tests/test_geoseries.py

@@ -139,6 +139,13 @@ class TestSeries(unittest.TestCase):
         # XXX: method works inconsistently for different pandas versions
         #self.na_none.fillna(method='backfill')
 
+    def test_coord_slice(self):
+        """ Test CoordinateSlicer """
+        # need some better test cases
+        self.assertTrue(geom_equals(self.g3, self.g3.cx[:, :]))
+        self.assertTrue(geom_equals(self.g3[[True, False]], self.g3.cx[0.9:, :0.1]))
+        self.assertTrue(geom_equals(self.g3[[False, True]], self.g3.cx[0:0.1, 0.9:1.0]))
+
     def test_geoseries_geointerface(self):
         self.assertEqual(self.g1.__geo_interface__['type'], 'FeatureCollection')
         self.assertEqual(len(self.g1.__geo_interface__['features']),