Pythonic shortcut for doubly nested for loops?

问题

Consider if I had a function that took a tuple argument (x,y), where x was in the range(X), and y in the range(Y), the normal way of doing it would be:

for x in range(X):
    for y in range(Y):
        function(x,y)

is there a way to do

for xy in something_like_range(X,Y):
    function(xy)

such that xy was a tuple (x,y)?

回答1:

You can use product from itertools

>>> from itertools import product
>>> 
>>> for x,y in product(range(3), range(4)):
...   print (x,y)
... 
(0, 0)
(0, 1)
(0, 2)
(0, 3)
(1, 0)
(1, 1)
(1, 2)
(1, 3)

... and so on

Your code would look like:

for x,y in product(range(X), range(Y)):
    function(x,y)

回答2:

You can use itertools.product():

from itertools import product
for xy in product(range(X), range(Y)):
    function(xy)

回答3:

Pythonic they are -> (modify according to your requirements)

>>> [ (x,y)   for x in range(2)   for y in range(2)]
[(0, 0), (0, 1), (1, 0), (1, 1)]

Generator version :

gen = ( (x,y)   for x in range(2)   for y in range(2) )
>>> for x,y in gen:
...     print x,y
... 
0 0
0 1
1 0
1 1

回答4:

Try product from itertools: http://docs.python.org/library/itertools.html#itertools.product

from itertools import product

for x, y in product(range(X), range(Y)):
    function(x, y)

回答5:

from itertools import product

def something_like_range(*sizes):
    return product(*[range(size) for size in sizes])

for a usage close to what you wanted:

for x,y in something_like_range(X,Y):
    your_function(x,y)

=)

来源：https://stackoverflow.com/questions/5462047/pythonic-shortcut-for-doubly-nested-for-loops