字典的增删改查

Posted 2020-11-02 爱灰灰的灰灰

字典

增

1.  有就覆盖，没有就添加

dic = {‘name‘: ‘老男孩‘, ‘age‘: 56, ‘hobby‘: ‘women‘}
dic[‘sex‘] = ‘LaddyBoy‘
dic[‘name‘] = ‘Alex‘  

2.  有就不变，没有就添加

dic = {‘name‘: ‘老男孩‘, ‘age‘: 56, ‘hobby‘: ‘women‘}
dic.setdefault(‘sex‘, ‘Laddyboy‘) 
dic.setdefault(‘name‘, ‘alex‘)
print(dic)

 

删

1.  pop  按照Key删除 ， 有返回值，返回删除对应键的值。

dic = {‘name‘: ‘老男孩‘, ‘age‘: 56, ‘hobby‘: ‘women‘}
print(dic.pop(‘age‘)) 
print(dic.pop(‘age1‘, ‘没有此键...‘))   #如果没有会报错，但是加上值就是返回你写的值
print(dic)

2.  clear  清空字典

dic = {‘name‘: ‘老男孩‘, ‘age‘: 56, ‘hobby‘: ‘women‘}
dic.clear() 
print(dic)

 3.  pop.item  随机删除，有返回值，返回为元祖，里边是删除的键对值

dic = {‘name‘: ‘老男孩‘, ‘age‘: 56, ‘hobby‘: ‘women‘}
print(dic.popitem())  
print(dic)

4.  del 删除整个字典

     按照键删除

dic = {‘name‘: ‘老男孩‘, ‘age‘: 56, ‘hobby‘: ‘women‘}
del dic[‘name‘]
print(dic)

改

1.  dic[‘name‘] = ‘Alex‘      有就覆盖没有就添加

2.  update 两个字典的更新

dic = {"name": "jin", "age": 18, "sex": "male"}
dic2 = {"name": "alex", "weight": 75}
dic2.update(dic)  # 将dic里面的所有键值对 覆盖添加到dic2中，dic不变
print(dic)  # {‘name‘: ‘jin‘, ‘age‘: 18, ‘sex‘: ‘male‘}
print(dic2)  # {‘name‘: ‘jin‘, ‘weight‘: 75, ‘age‘: 18, ‘sex‘: ‘male‘}

 

查

1.  有就返回值，没有报错

# 1,dic[‘name‘]
dic = {‘name‘: ‘老男孩‘, ‘age‘: 56, ‘hobby‘: ‘women‘}
print(dic[‘name‘])

2.  有就返回值 ， 没有返回None

2,dic.get(‘name‘)

dic = {‘name‘: ‘老男孩‘, ‘age‘: 56, ‘hobby‘: ‘women‘}print(dic.get(‘name‘))
print(dic.get(‘name1‘))
print(dic.get(‘name1‘, ‘sb没有此键‘))

3.  for循环查询

    dic.keys(), dic.values(), dic.items() #类似于list但不是list的类型。

# 循环键

dic = {‘name‘: ‘老男孩‘, ‘age‘: 56, ‘hobby‘: ‘women‘}
for key in dic.keys():     
    print(key)

# 循环值

dic = {‘name‘: ‘老男孩‘, ‘age‘: 56, ‘hobby‘: ‘women‘}
for value in dic.values():
    print(value)

   # 循环 键 和 值   分别赋值

dic = {‘name‘: ‘老男孩‘, ‘age‘: 56, ‘hobby‘: ‘women‘}
for k,v in dic.items(): 
    print(k,v)