python numpy中的组合数学

直接使用python itertools:

In [134]: import itertools
In [135]: a,b = [1,2,3], [4,5,6]
In [137]: list(itertools.product(a,b))
Out[137]: [(1, 4), (1, 5), (1, 6), (2, 4), (2, 5), (2, 6), (3, 4), (3, 5), (3, 6)]

或作为数组:

In [145]: np.array(list(itertools.product(a,b)))
Out[145]: 
array([[1, 4],
       [1, 5],
       [1, 6],
       [2, 4],
       [2, 5],
       [2, 6],
       [3, 4],
       [3, 5],
       [3, 6]])