如果list里里面的元素是数字，‘1’也是可以的，那么我们可以使用np.ravel

a = [[1,2,3], [5, 2, 8], [7,8,9]]

list(np.ravel(a))
#[1, 2, 3, 5, 2, 8, 7, 8, 9]

对于不规则List
c=[[‘云阳站’], [‘双江’, ‘木古’], [‘滨双线’], [‘滨双线’, ‘云田线’], [‘云田线’, ‘田红线’]]

c=[['云阳站'], ['双江', '木古'], ['滨双线'], ['滨双线', '云田线'], ['云田线', '田红线']]
def flat(a):
    l= []
    for i in a:
        if type(i) is list:
            for j in i:
                l.append(j)
        else:
            l.append(i)
    return(l)

print(flat(c))