command....@alexbbs.twbbs.org (§ä´m¦Û¤vª�...@¤ù¤Ñ) writes:
> if i want to create a list of list which size is 2**25
>
> how should i do it?
>
> i have try [ [] for x in xrange(2**25) ]
>
> but it take too long to initial the list
>
> is there any suggestion?
What is it you want to do with the result?
If you want to lazy-evaluate the expression, what you're looking for is
a generator. You can get one easily by writing a generator expression:
>>> foo = ([] for x in xrange(2**25))
>>> foo
<generator object at 0x103dc788>
>>> for item in foo:
... do_interesting_stuff_with(item)
If what you want is to have a huge multi-dimensional array for numerical
analysis, lists may not be the best option. Instead, install the
third-party NumPy library and use its types. You don't show what kind of
data you want in your array, but assuming you want integers initialised
to zero:
>>> import numpy
>>> foo = numpy.zeros((2**25, 0), int)
>>> foo
array([], shape=(33554432, 0), dtype=int32)
Other quick ways of constructing NumPy arrays exist, see
<URL:http://docs.scipy.org/doc/numpy/reference/routines.array-creation.html>.
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`\ —Niels Bohr |
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Ben Finney
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