Python: Dynamic nested for loops each with different range

问题

I want to create a code that can iterate over a dynamic number (N) of nested loops each with different range. For example:

N=3 
ranges=[[-3, -2, -1, 0, 1, 2, 3],
 [-5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5],
  [-3, -2, -1, 0, 1, 2, 3]]

for x in ranges[0]:
    for y in ranges[1]:
        for z in range[2]:
            variable=[x, y, z]

Im new to python. As I went over similar questions posted here I have the understanding that this can be done with recursion or itertools. However, none of the answers posted solve this problem for a different range at each level. The closest posted question similar to mine was Variable number of nested for loops with fixed range . However, the answer posted by user633183 is coded in python 3.X and I am coding in python 2.7 so I couldn't implement it as some of its code does not work on python 2.7. Can you please help me to code this problem. Thanks!

回答1:

Your code is equivalent to itertools.product:

print(list(itertools.product(*ranges)))

回答2:

So, if I am understanding your question correctly, you want the values being iterated over to be [-3, -5, -3], [-2, -4, -2].... This can be accomplished easily with zip function built into python:

for x in zip(*ranges):
    # Do something with x

x will take on a tuple of all the first values, then a tuple of all the second values, etc, stopping when the shortest list ends. Using this * splat notation avoids even having to know about the number of lists being combined.

来源：https://stackoverflow.com/questions/50636404/python-dynamic-nested-for-loops-each-with-different-range