python 求列表的交集，并集，差集

#coding=utf-8

def foo(list1,list2):

#求交集

ret1 = [i for i in list1 if i in list2]

ret2 = list(set(list1).intersection(set(list2)))

ret3 = list(set(list1) & set(list2))

print 'ret1:',ret1

print 'ret2:',ret2

print 'ret3:',ret3

#求并集

ret4 = list(set(list1).union(set(list2)))

ret5 = list(set(list1) | set(list2))

print 'ret4:',ret4

print 'ret5:',ret5

 

#求差集

ret6 = list(set(list1).difference(set(list2)))

ret7 = [i for i in list1 if i not in list2]

ret8 = list(set(list1) - set(list2))

print 'ret6:',ret6

print 'ret7:',ret7

print 'ret8:',ret8

if __name__ == '__main__':

list1 = [1,2,3,4,5,6]

list2 = [3,4,5,6,7]

foo(list1,list2)

 打印出来：

In [7]: %run set.py
ret1: [3, 4, 5, 6]
ret2: [3, 4, 5, 6]
ret3: [3, 4, 5, 6]
ret4: [1, 2, 3, 4, 5, 6, 7]
ret5: [1, 2, 3, 4, 5, 6, 7]
ret6: [1, 2]
ret7: [1, 2]
ret8: [1, 2]