Large Dictionaries

[Duncan Booth]

John Machin wrote:

>> (my dictionary values are all None).
> 
> So in fact all you need is a set. Have you experimented with the Python
> 2.5 alpha?
> 
I don't think that will help him: my timings work out about the same on 
2.4.2 or 2.5a2. As I pointed out, the bottleneck is creating the tuples. 
Creating either a dictionary or a set from 5 million tuples takes a similar 
amount of time (about 6 seconds on my system).

BTW, a string key is quite a bit faster than the tuples, even though you 
end up with as many temporary tuples during the process:

>>> scale = 2**32
>>> data = [ "%d:%d" % (i*scale,i) for i in range(5000000) ]
>>> d = set(data)

takes about 18 seconds to create the data list and 5 for the set.