python 字典

#字典是k-v形式，无序。key唯一
students={‘0001‘:‘张三‘,‘0002‘:‘李四‘,‘0003‘:‘王五‘}

#字典方法
print(students.items())  #打印字典里k-v
print(students.keys())  #打印字典的key值
print(students.values()) #打印字典的value值

add={‘0001‘:‘hi‘,‘a‘:‘b‘,4:5}  #update方法更新字典
students.update(add)
print(students)

#查找
print(‘0001‘in students) #通过key判断
print(students.get(‘0001‘))  #通过get获取
print(students.get(‘0011‘))  #key不存在，返回None
print(students[‘0001‘])  #直接通过key获取v
print(students[‘0011‘])  #key不存在，会报错

#增加
students[‘0004‘]=‘new‘     
print(students)
students.setdefault(‘0005‘,‘default‘)   #用setdefault方法增加
print(students)

#修改
students[‘0004‘]=‘change‘  #指定key修改
print(students)
#删除
students.pop(‘0004‘)  #删除法1
print(students)
del students[‘0004‘]  #删除法2
print(students)
students.popitem()   #随机删除
print(students)
students.clear()  #清空字典
print(students)
#多级嵌套字典
people = {
   ‘田雨‘:{
      ‘age‘:18,
      ‘money‘:200000,
      ‘clothes‘:‘100套‘,
      ‘hzp‘:‘n多‘,
      ‘shoes‘:[‘nike‘,‘addis‘,‘lv‘,‘chanle‘]
   },
   ‘张流量‘:{
      ‘金库‘:‘2000w‘,
      ‘house‘:[‘三环一套‘,‘4环2套‘],
      ‘cars‘:    {
            ‘japan‘:[‘普拉多‘,‘兰德酷路泽‘],
            ‘usa‘:[‘林肯‘,‘凯迪拉克‘,‘福特‘],
            ‘china‘:[‘五菱宏光‘,‘qq‘,‘红旗‘]
         }
   }
}
print(people[‘张流量‘][‘cars‘][‘china‘][1])    #嵌套字典查询
people[‘张流量‘][‘cars‘][‘china‘].append(‘吉利‘)  #字典嵌套列表追加
print(people)
for i in people:    #循环打印key
    print(i)
for k,v in people.items():
    print(k,v)