Ladislav Andel wrote: > what would be the most efficient way to do following? > > I have a list of dictionaries taken from DB e.g. > dblist = [{'id:1, 'host':'google.com','ip_address':'1.2.3.4'}, > {'id:3, 'host':'yahoo.com','ip_address':'5.6.7.8'}, > {'id:9, 'host':'msn.com','ip_address':'11.3.2.3'}] > > and list of object instances in memory(it's just for example) > which are looping within itself and testing particular hosts > > memlist = [<instance 1>,<instance 2>] > memlist[0].id is 1 and memlist[0].host is google.com etc. > memlist[1].id is 9 and memlist[1].host is msn.com etc. > > Now I want to add a new instance to memlist since id=3(in dblist) is not > in memlist. > How would you iterate through it and insert a new instance? > > The result should be: > memlist = [<instance 1>,<instance 2>, <instance 3>] > memlist[0].id is 1 and memlist[0].host is google.com etc. > memlist[1].id is 3 and memlist[1].host is yahoo.com etc. > memlist[2].id is 9 and memlist[2].host is msn.com etc.
You should replace the memlist with a dictionary using (host, id) tuples as the keys. Here's an example that uses a set but requires you to modify the <instance N> class: dblist = [{'id':1, 'host':'google.com','ip_address':'1.2.3.4'}, {'id':3, 'host':'yahoo.com','ip_address':'5.6.7.8'}, {'id':9, 'host':'msn.com','ip_address':'11.3.2.3'}] class Item(object): def __init__(self, id, host, **discarded): self._tuple = (id, host) def __hash__(self): return hash(self._tuple) def __eq__(self, other): return self._tuple == other._tuple def __repr__(self): return "Item(id=%r, host=%r)" % self._tuple items = set([Item(1, "google.com")]) for d in dblist: item = Item(**d) if item not in items: print "adding", item items.add(item) else: print item, "already there" Peter -- http://mail.python.org/mailman/listinfo/python-list