Refactor Graph.filter to use list comprehension (#54)

Author: arun1729

cog/torque.py

@@ -421,9 +421,7 @@ def filter(self, func):
         '''
             Applies a filter function to the vertices and removes any vertices that do not pass the filter.
         '''
-        for v in self.last_visited_vertices:
-            if not func(v.id):
-                self.last_visited_vertices.remove(v)
+        self.last_visited_vertices = [v for v in self.last_visited_vertices if func(v.id)]
         return self
 
     def sim(self, word, operator, threshold, strict=False):

setup.py

@@ -2,7 +2,7 @@
 
 
 setup(name='cogdb',
-      version='3.0.8',
+      version='3.0.9',
       description='Persistent Embedded Graph Database',
       url='http://github.com/arun1729/cog',
       author='Arun Mahendra',

test/test_torque6.py

@@ -97,6 +97,15 @@ def test_filter_int(self):
         self.assertTrue(expected == actual)
         g.close()
 
+    def test_filter_multiple_non_matches(self):
+        g = Graph(graph_name="test6", cog_home=DIR_NAME)
+        traversal = g.v(["greg", "tom", "alice"])
+        returned = traversal.filter(func=lambda x: x == 'alice')
+        self.assertIs(returned, traversal)
+        expected = {'result': [{'id': 'alice'}]}
+        self.assertTrue(expected == returned.all())
+        g.close()
+
     @classmethod
     def tearDownClass(cls):
         shutil.rmtree("/tmp/" + DIR_NAME)