creating really big lists

Paul Rudin paul.nospam at
Wed Sep 5 12:00:38 CEST 2007

Dr Mephesto <dnhkng at> writes:

> Hi!
> I would like to create a pretty big list of lists; a list 3,000,000
> long, each entry containing 5 empty lists. My application will append
> data each of the 5 sublists, so they will be of varying lengths (so no
> arrays!).
> Does anyone know the most efficient way to do this? I have tried:
> list = [[[],[],[],[],[]] for _ in xrange(3000000)]
> but its not soooo fast. Is there a way to do this without looping?

You can do:

   [[[],[],[],[],[]]] * 3000000

although I don't know if it performs any better than what you already

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