Python: fastest way to create a list of n lists

by

The probably only way which is marginally faster than 

d = [[] for x in xrange(n)]

is

from itertools import repeat
d = [[] for i in repeat(None, n)]

It does not have to create a new int object in every iteration and is about 15 % faster on my machine.

Edit: Using NumPy, you can avoid the Python loop using

d = numpy.empty((n, 0)).tolist()

but this is actually 2.5 times slower than the list comprehension.

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