随机循环

Question

lst = ['mylist1','mylist2','mylist3']
for x in lst:
    for r in xrange(2):
        print x

输出：（将列表中的元素重复两次）

[root@localhost ~]# python test.py
mylist1
mylist1
mylist2
mylist2
mylist3
mylist3

如何随机选择元素：

mylist3
mylist1
mylist3
mylist2
mylist2
mylist1

Answer 1

您可以先使用列表extend()将列表中的每个元素加倍，然后对列表进行随机播放

from random import shuffle

lst = ['mylist1','mylist2','mylist3']
lst = lst.extend(lst) # repeat items twice
shuffle(lst)
for x in lst:
    print(x)

Answer 2

或*（乘法运算符）：

lst = lst*2 # repeat items twice
shuffle(lst)
for x in lst:
    print(x)

或list comprehension：

lst = [x for i in range(2) for x in lst] # repeat items twice
shuffle(lst)
for x in lst:
    print(x)