Merge pull request #7 from QuLogic/domain-of-validity

Fix domain of validity XML searching

pyepsg.py

@@ -190,11 +190,10 @@ def domain_of_validity(self):
         For example::
 
             >>> print(get(21781).domain_of_validity())
-            [5.97, 10.49, 45.83, 47.81]
+            [5.96, 10.49, 45.82, 47.81]
 
 
         """
-        # TODO: Check for gmd:EX_GeographicBoundingBox and blow up otherwise.
         # TODO: Generalise interface to return a polygon? (Can we find
         # something that uses a polygon instead?)
         domain = self.element.find(GML_NS + 'domainOfValidity')
@@ -204,17 +203,17 @@ def domain_of_validity(self):
         xml = requests.get(url).content
         gml = ET.fromstring(xml)
 
-        def extract_bound(i, tag):
-            # TODO: Figure out if this is our problem or ET's.
-            # `find` isn't returning anything :(
-            # ns = '{http://www.isotc211.org/2005/gmd}'
-            # bound = gml.find(ns + tag)
-            bound = gml[1][0][1][0][i]
-            return float(bound[0].text)
+        def extract_bound(tag):
+            ns = '{http://www.isotc211.org/2005/gmd}'
+            xpath = './/{ns}EX_GeographicBoundingBox/{ns}{tag}/'.format(
+                ns=ns,
+                tag=tag)
+            bound = gml.find(xpath)
+            return float(bound.text)
 
         tags = ('westBoundLongitude', 'eastBoundLongitude',
                 'southBoundLatitude', 'northBoundLatitude')
-        bounds = [extract_bound(i, tag) for i, tag in enumerate(tags)]
+        bounds = [extract_bound(tag) for tag in tags]
         return bounds