Python: fastest way to create a list of n lists

Question

So I was wondering how to best create a list of blank lists:

[[],[],[]...]

Because of how Python works with lists in memory, this doesn\'t

Answer 1

The list comprehensions actually are implemented more efficiently than explicit looping (see the dis output for example functions) and the map way has to invoke an ophaque callable object on every iteration, which incurs considerable overhead overhead.

Regardless, [[] for _dummy in xrange(n)] is the right way to do it and none of the tiny (if existent at all) speed differences between various other ways should matter. Unless of course you spend most of your time doing this - but in that case, you should work on your algorithms instead. How often do you create these lists?