remove duplicates from list *preserving order*

[Steven Bethard]

I'm sorry, I assume this has been discussed somewhere already, but I 
found only a few hits in Google Groups...  If you know where there's a 
good summary, please feel free to direct me there.


I have a list[1] of objects from which I need to remove duplicates.  I 
have to maintain the list order though, so solutions like set(lst), etc. 
will not work for me.  What are my options?  So far, I can see:

def filterdups(iterable):
     result = []
     for item in iterable:
         if item not in result:
             result.append(item)
     return result

def filterdups(iterable):
     result = []
     seen = set()
     for item in iterable:
         if item not in seen:
             result.append(item)
             seen.add(item)
     return result

def filterdups(iterable):
     seen = set()
     for item in iterable:
         if item not in seen:
             seen.add(item)
             yield item

Does anyone have a better[2] solution?

STeve

[1] Well, actually it's an iterable of objects, but I can convert it to 
a list if that's helpful.

[2] Yes I know, "better" is ambiguous.  If it helps any, for my 
particular situation, speed is probably more important than memory, so 
I'm leaning towards the second or third implementation.