Introduction to Python product function

Introduce the product function through from itertools import product.

The Product function can realize the Cartesian product of the matrix

import itertools
for item in itertools.product([1,2],[10,20]):
    print(item)

'''
(1, 10)
(1, 20)
(2, 10)
(2, 20)
'''

iterables are iterable objects, and repeat specifies that iterable repeats several times, namely:

product(A,repeat=3)等价于product(A,A,A)

 product('ABCD', 'xy') --> Ax Ay Bx By Cx Cy Dx Dy

 product(range(2), repeat=3)  等价于product([0,1],[0,1],[0,1]) 

--> 000 001 010 011 100 101 110 111