Merge pull request #37 from cfarmer/bounds

changing the way 'bounds' is implemented to match shapely

geopandas/geoseries.py

@@ -5,6 +5,7 @@ import fiona
 from fiona.crs import from_epsg
 import numpy as np
 from pandas import Series, DataFrame
+from pandas.util.decorators import cache_readonly
 import pyproj
 from shapely.geometry import shape, Polygon, Point
 from shapely.geometry.collection import GeometryCollection
@@ -295,7 +296,6 @@ class GeoSeries(Series):
     # Other operations
     #
 
-    # should this return bounds for entire series, or elementwise?
     @property
     def bounds(self):
         """Return a DataFrame of minx, miny, maxx, maxy values of geometry objects"""
@@ -303,6 +303,21 @@ class GeoSeries(Series):
         return DataFrame(bounds,
                          columns=['minx', 'miny', 'maxx', 'maxy'],
                          index=self.index)
+                         
+    @cache_readonly
+    def total_bounds(self):
+        """Return a single bounding box (minx, miny, maxx, maxy) for all geometries
+
+        This is a shortcut for the following:
+        >>> aggregator = dict(minx=np.nanmin, miny=np.nanmin,
+                              maxx=np.nanmax, maxy=np.nanmax)
+        >>> series.bounds.groupby(lambda x: 1).agg(aggregator)
+        """
+
+        aggregator = dict(minx=np.nanmin, miny=np.nanmin,
+                          maxx=np.nanmax, maxy=np.nanmax)
+        bbox = self.bounds.groupby(lambda x: 1).agg(aggregator)
+        return tuple(bbox.values[0].tolist())
 
     def buffer(self, distance, resolution=16):
         return GeoSeries([geom.buffer(distance, resolution) for geom in self],

tests/test_geoseries.py

@@ -285,4 +285,9 @@ class TestSeries(unittest.TestCase):
         res = self.g4.skew(ys=skew, origin=Point(0,0))
         self.assertTrue(geom_almost_equals(self.g4, res.skew(ys=-skew, 
             origin=Point(0,0))))
+            
+    def test_total_bounds(self):
+        bbox = self.sol.x, self.sol.y, self.esb.x, self.esb.y
+        self.assertEqual(self.landmarks.total_bounds, bbox)
+        self.assertEqual(self.g1.total_bounds, (0, 0, 1, 1))