Python 字典，,字典的定义dic =

Python 字典，,字典的定义dic =

字典的定义

dic = {"name":"zhangsan","age":7,"val":{"math":60,"eng":80}}

值的输出

print dic["name"]   #zhangsanprint dic["val"]["math"]  #60

字典的遍历

dic = {"name":"zhangsan","age":7,"val":{"math":60,"eng":80}}print "only key"for key in dic.keys():    print keyprint "only val"for val in dic.values():    print valprint "both"for key,val in dic.items():    print key,val
输出的结果:

$ python test.py
only key
age
name
val
only val
7
zhangsan
{‘math‘: 60, ‘eng‘: 80}
both
age 7
name zhangsan
val {‘math‘: 60, ‘eng‘: 80}

$ python test.py
only key
age
name
val
only val
7
zhangsan
{‘math‘: 60, ‘eng‘: 80}
both
age 7
name zhangsan
val {‘math‘: 60, ‘eng‘: 80}

Python 中set

set()函数创建一个无序不重复元素集，可进行关系测试，删除重复数据，还可以计算交集、差集、并集等。

set 持有一系列元素，这一点和 list 很像，但是set的元素没有重复，而且是无序的，这点和 dict 的 key很像。

s = set([‘a‘,‘b‘,‘c‘])print s   #输出set([‘a‘, ‘c‘, ‘b‘])s = set([‘a‘,‘b‘,‘c‘,‘a‘])print s   #输出set([‘a‘, ‘c‘, ‘b‘])

a = set([‘a‘,‘b‘,‘c‘])b = set([‘a‘,‘b‘,‘c‘,‘d‘])print a & b  #交集   输出set([‘a‘, ‘c‘, ‘b‘])print a | b  #并集   输出set([‘a‘, ‘c‘, ‘b‘, ‘d‘])print b - a  #差集   输出set([‘d‘])
print a - b  #差集   输出set([])

Python 字典