python代码得到列表list的交集与差集

交集
b1=[1,2,3]
b2=[2,3,4]
b3 = [val for val in b1 if val in b2]
print b3

差集

b1=[1,2,3]
b2=[2,3,4]
b3 = [val for val in b1 if val not in b2]
print b3

差集实例
———-
#/bin/env python
# -*- coding:utf-8 -*-

f = open(‘C:diff_dealerexcel.txt’)
excel = f.readlines()
f.close()

f= open(‘C:diff_dealerdb.txt’)
db = f.readlines()
diff = [val for val in db if val not in excel]
f.close()

f = open(‘C:diff_dealerdiff.txt’, ‘w’)
f.writelines(diff)
f.close()

print diff