字典类型内置方法

字典

1.作用

对于值添加描述信息使用它

2.定义方式

用{}以逗号隔开加入键值对key:value

info_dict = {'name':'wangdapao','age':18,'height':120,'gender':'famale','hobby_list':['dapao','666']}

3.内置方法

优先掌握

1.按key取值,即可取也可以改变
print(info_dict['hobby_list'])   #['dapao','666','233']

info_dict['age'] = 20
print(info_dict)      #{'name':'wangdapao','age':20,'height':120,'gender':'famale','hobby_list':['dapao','666']}

2.长度len
print(len(info_dict))     #5

3. in/not in
print('name' in info_dict)    #True

4.for循环
for i in info_dict:
    print(i)
    
5.keys/values/items，items用的最多，)
print(list(info_dict.keys()))   #list
print(list(info_dict.values()))  #list
print(list(info_dict.items()))   #list

for i in info_dict.values():
    print(i)
info_dict = {'name':'wangdapao','age':20,'height':120,'gender':'famale','hobby_list':['dapao','666']}
print(info_dict.items())

for i in info_dict.items():
    print(i)

for k,v in info_dict.items():
    print(k,v)
    
lt = [[1,2,3],[2,3,4],[5,6,7]]
for a,b,c in lt:
    print(a,b,c)

需要掌握

info_dict = {'name':'wangdapao','age':20,'height':120,'gender':'famale','hobby_list':['dapao','666']}
print(info_dict.copy())

info_dict.pop('name')
print(info_dict)

info_dict.popitem()     #早起的时候是随机删除的，但是由于python3底层优化了字 print(info_dict)         典，让字典看的貌似有序了，所以默认删除最后一个


info_dict.clear()
print(info_dict)

(info_dict.get('age'))
#print(info_dict['name'])
print(info_dict.get('name','nick'))  #如果有，就返回真正的值，如果没有，默                                       认返回None,也可以指定返回
if jiangpin_lan_dict.get(reward) is None: #None和小整数池一样固定不变的id


info_dict.setdefault('gender',123123) #有则不变,无则往里面追加了值
print(info_dict)

info_dict.update({'a':1})
print(info_dict)

4.存一个值还是多个值

多个值

5.有序or无序

无序

6. 可变or不可变(重点)

可变

dic = {'a':1}
print(id(dic))
dic['b'] = 1
print(id(dic))