Added an insert method to Entity. This allows a child to be inserted into a specified position in the child_list which effects position in the PDB output.

Author: benreynwar

Bio/PDB/Entity.py

@@ -84,6 +84,16 @@ def add(self, entity):
         self.child_list.append(entity)
         self.child_dict[entity_id]=entity
 
+    def insert(self, pos, entity):
+        "Add a child to the Entity at a specified position."
+        entity_id=entity.get_id()
+        if self.has_id(entity_id):
+            raise PDBConstructionException( \
+                "%s defined twice" % str(entity_id))
+        entity.set_parent(self)
+        self.child_list[pos:pos] = [entity]
+        self.child_dict[entity_id]=entity        
+
     def get_iterator(self):
         "Return iterator over children."
         for child in self.child_list: