yep, thats why I'm asking :) On Sep 5, 12:22 pm, "Diez B. Roggisch" <[EMAIL PROTECTED]> wrote: > Paul Rudin wrote: > > Dr Mephesto <[EMAIL PROTECTED]> 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 > > have. > > You are aware that this is hugely different, because the nested lists are > references, not new instances? Thus the outcome is most probably (given the > gazillion of times people stumbled over this) not the desired one... > > Diez
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