PEP 8 fixes

pandana/network.py

@@ -17,13 +17,13 @@ def reserve_num_graphs(num):
     """
     This function was previously used to reserve memory space for multiple
     graphs. It is no longer needed in Pandana 0.4+, and will be removed in a
-    future version. 
-    
+    future version.
+
     Parameters
     ----------
     num : int
         Number of graph to be reserved in memory
-    
+
     """
     warnings.warn(
         "Function reserve_num_graphs() is no longer needed in Pandana 0.4+\
@@ -188,7 +188,7 @@ def shortest_path(self, node_a, node_b, imp_name=None):
         -------
         A numpy array of the nodes that are traversed in the shortest
         path between the two nodes
-        
+
         """
         # map to internal node indexes
         node_idx = self._node_indexes(pd.Series([node_a, node_b]))
@@ -236,7 +236,7 @@ def set(self, node_ids, variable=None, name="tmp"):
         Returns
         -------
         Nothing
-        
+
         """
         if variable is None:
             variable = pd.Series(np.ones(len(node_ids)), index=node_ids.index)