firstly "set" is a built in type in 2.4, and it is bad form to name variables the same as existing types or modules - it can lead to confusing code and subtle bugs.
Secondly, the sets.Set class used in f6 is implemented in Python, both in 2.3 and 2.4, while the set builtin type is implemented in C so should be significantly faster.
Here is alternative order-preserving function. I have not timed it, but it should be pretty fast:
def f7(seq): seen = set() return [ x for x in seq if x not in seen and not seen.add(x)]
Comment
firstly "set" is a built in type in 2.4, and it is bad form to name variables the same as existing types or modules - it can lead to confusing code and subtle bugs.
Secondly, the sets.Set class used in f6 is implemented in Python, both in 2.3 and 2.4, while the set builtin type is implemented in C so should be significantly faster.
Here is alternative order-preserving function. I have not timed it, but it should be pretty fast:
def f7(seq):
seen = set()
return [ x for x in seq if x not in seen and not seen.add(x)]