python字典

字典即为放在花括号{}中一系列键值对的集合，值可以使数字、字符、集合等。

字典创建

>>> employee_1 = {'name': 'david', 'dept': 'ops', 'post': 'NOC', 'salary': 9999}
>>>
>>> type(employee_1)
<class 'dict'>

访问字典中的数据

>>> print(employee_1)
{'name': 'david', 'dept': 'ops', 'post': 'NOC', 'salary': 9999}
>>> 
>>> print(employee_1['name'])
david
>>>
>>> print("Welcome our new colleague: " + employee_1['name'] + ", " + "His post is: " + employee_1['post'] + ".")
Welcome our new colleague: david, His post is: NOC.

 修改字典中的数据

>>> print(employee_1)
{'name': 'david', 'dept': 'ops', 'post': 'NOC', 'salary': 9999}
>>>
>>> employee_1['salary'] = 12000
>>> 
>>> employee_1
{'name': 'david', 'dept': 'ops', 'post': 'NOC', 'salary': 12000}

向字典中添加新的键值对

>>> employee_1
{'name': 'david', 'dept': 'ops', 'post': 'NOC', 'salary': 12000}
>>> 
>>> employee_1['id'] = 113
>>> 
>>> employee_1
{'name': 'david', 'dept': 'ops', 'post': 'NOC', 'salary': 12000, 'id': 113}

删除一个键值对

>>> employee_1
{'name': 'david', 'dept': 'ops', 'post': 'NOC', 'salary': 12000, 'id': 113}
>>> 
>>> del employee_1['id']
>>> 
>>> employee_1
{'name': 'david', 'dept': 'ops', 'post': 'NOC', 'salary': 12000}

遍历字典

遍历字典中的键值对

employee_1 = {'name': 'david', 'dept': 'ops', 'post': 'NOC', 'salary': 12000, 'id': 113}
for key, value in employee_1.items():
    print("\nkey: %s" % key)
    print("value: %s" % value)

输出

key: name
value: david

key: dept
value: ops

key: post
value: NOC

key: salary
value: 12000

key: id
value: 113

遍历字典中的键

employee_1 = {'name': 'david', 'dept': 'ops', 'post': 'NOC', 'salary': 12000, 'id': 113}
for key in employee_1.keys():
    print("key: %s" % key)

 输出

key: name
key: dept
key: post
key: salary
key: id

遍历字典中的值

employee_1 = {'name': 'david', 'dept': 'ops', 'post': 'NOC', 'salary': 12000, 'id': 113}
for value in employee_1.values():
    print("key: %s" % value)

输出

key: david
key: ops
key: NOC
key: 12000
key: 113