Python中字典的操作

1、字典key-value,key是不能重复的stu_info={"name":"王志华","age":18,"addr":"北京"}2、取值，查print(stu_info[‘name‘])print(stu_info[‘age‘])print(stu_info[‘addr‘])# print(stu_info[‘we‘])  #取不存在的key的值，会报key不存在的错误#.get方法取值print(stu_info.get(‘name‘))print(stu_info.get(‘we‘)) #取不存在的key的值，会返回None,取值最好用.get方法，不会报错print(stu_info.get(‘login‘,500)) #如果值不存在，就返回逗号后面的值，这个返回500

2、修改stu_info[‘addr‘]=‘上海‘print(stu_info)

3、新增stu_info[‘phone‘]=123456stu_info.setdefault(‘email‘,‘[email protected]‘)print(stu_info)#新增一个不存在的key,不会修改value的值stu_info.setdefault(‘age‘,‘19‘)print(stu_info)

4、删除stu_info.pop(‘email‘)print(stu_info)del stu_info[‘age‘]print(stu_info)

# stu_info.popitem() #从字典中随机删除一个元素# stu_info.clear() #清空字典stu_info[‘age‘]=20print(stu_info)5、把一个字典加到另外一个字典里d1={‘b‘:1}d2={‘a‘:2}d1.update(d2)#把d2加到d1中print(d1)6、循环字典print(stu_info.keys())#打印所有的keyprint(stu_info.values()) #打印所有的values#直接循环字典，打印出来都是字典中的keyfor i in stu_info:    print(i)#判断key是否存在print(‘name‘in stu_info.keys())print(‘name‘ in stu_info)

#第一种，这种效率比第二种效率高第一种，取key和value的值：for i in stu_info:    s=‘%s=>%s‘%(i,stu_info.get(i))    print(s)#第二种for k,v in stu_info.items():    print(‘%s=>%s‘%(k,v))

print(stu_info.items())

7、字典的嵌套

#字典嵌套stu_info={    ‘xiaoming‘:{"password":123456,"phone":1323214,"age":18,"addr":"北京"},    "xiaohei":{"password": 123456,"phone": 132321,"age": 18,"addr": "上海"}}print(stu_info[‘xiaoming‘][‘phone‘])d = {    ‘春波‘:{        "car":{‘BMW‘:5,‘BENZ‘:3,‘audi‘:3,‘byd‘:4},        "house":["北京",‘南京‘,‘上海‘],        "money":1000000,},    ‘乔美玲‘:{        "bag":[‘xx‘,‘lv‘,],        "house":[‘三环‘,‘4环‘],        "hzp":[‘skii‘,‘ysl‘],        ‘language‘:{            ‘普通话‘:10,            ‘东北话‘:20,            ‘日语‘:0,            ‘英语‘:4        }    }}

#1、马春波卖了一套上海的房子，买了500百万d[‘春波‘][‘house‘].pop(-1)print(d[‘春波‘][‘house‘])

d[‘春波‘][‘money‘]+=5000000print(d[‘春波‘][‘money‘])#2、算一下马春波有多少辆车car_num=d[‘春波‘][‘car‘].values()print(sum(car_num))#3、春波花了100百万买了一辆莱斯莱斯d[‘春波‘][‘money‘]-=1000000print(d[‘春波‘][‘money‘])

d[‘春波‘][‘car‘].setdefault(‘莱斯莱斯‘,1)print(d[‘春波‘][‘car‘])

#4、乔美玲的东北话从20级变成了10级d[‘乔美玲‘][‘language‘][‘东北话‘]-=10print(d[‘乔美玲‘][‘language‘][‘东北话‘])#5、乔美玲会哪几种语言for k in d[‘乔美玲‘][‘language‘]:    print(k)

原文地址：https://www.cnblogs.com/qiuqiu64/p/10004525.html