dict-字典功能介绍

叨逼叨：
#字典  可变类型 意思就是修改的是自己本身
#可变类型，当修改后，内存里的值也会对应着修改
#不可变类型，当修改后，会在内存里开启一块新的空间，放新的值

#1.清空

# name = {
#     'name':'alex',
#     'age':23,
#     'gender':'女'
# }
# name.clear()
# print(name)

举例

  def clear(self): # real signature unknown; restored from __doc__
        """ D.clear() -> None.  Remove all items from D. """
        pass

clear

#2.拷贝复制 浅拷贝

# name = {
#     'name':'alex',
#     'age':23,
#     'gender':'女'
# }
# v = name.copy()
# print(v)
# print(name)

举例

    def copy(self): # real signature unknown; restored from __doc__
        """ D.copy() -> a shallow copy of D """
        pass

copy

#3.根据key 取value的值

# name = {
#     'name':'alex',
#     'age':23,
#     'gender':'女'
# }
# v = name.get('name') #这个方式以后会常用 没有取值不报错
# v1 = name['name'] #没有取到  会报错
# print(v)
# print(v1)

举例

    def get(self, k, d=None): # real signature unknown; restored from __doc__
        """ D.get(k[,d]) -> D[k] if k in D, else d.  d defaults to None. """
        pass

get

#4.取出key和value

# name = {
#     'name':'alex',
#     'age':23,
#     'gender':'女'
# }
# v = name.items()
# print(v)
# #打印结果：
# #dict_items([('name', 'alex'), ('age', 23), ('gender', '女')])
# for item in name.items():
#     print(item)
#     #打印结果
#     # ('name', 'alex')
#     # ('age', 23)
#     # ('gender', '女')
# for key,value in name.items():
#     print(key,value)
#     #打印结果
#     #name alex
#     #age 23
#     #gender

举例

    def items(self): # real signature unknown; restored from __doc__
        """ D.items() -> a set-like object providing a view on D's items """
        pass

items

#5.单独取出key

# name = {
#     'name':'alex',
#     'age':23,
#     'gender':'女'
# }
# v = name.keys()
# print(v)
# #打印结果
# #dict_keys(['name', 'age', 'gender'])
# for i in name.keys():
#     print(i)
#     #打印结果
#     #name
#     #age
#     #gender

举例

    def keys(self): # real signature unknown; restored from __doc__
        """ D.keys() -> a set-like object providing a view on D's keys """
        pass

keys

#6.单独取出value

# name = {
#     'name':'alex',
#     'age':23,
#     'gender':'女'
# }
# v = name.values()
# print(v)
# for i in name.values():
#     print(i)
# #打印结果分别如下
# # dict_values(['alex', 23, '女'])
# # alex
# # 23
# # 女

举例

    def values(self): # real signature unknown; restored from __doc__
        """ D.values() -> an object providing a view on D's values """
        pass

values

#7.删除并获取对应的value值

# name = {
#     'name':'alex',
#     'age':23,
#     'gender':'女'
# }
# v = name.pop('name')
# print(v)
# print(name)
#还可以这么删除
# v = {
#     'name':'alex',
#     'password':'123',
#     'gender':'girl'
# }
# del v['name']
# print(v)

举例

    def pop(self, k, d=None): # real signature unknown; restored from __doc__
        """
        D.pop(k[,d]) -> v, remove specified key and return the corresponding value.
        If key is not found, d is returned if given, otherwise KeyError is raised
        """
        pass

pop

#8.随机删除键值对，并获取到删除的键值对

# name = {
#     'name':'alex',
#     'age':23,
#     'gender':'女'
# }
# v = name.popitem()
# print(v)
# print(name)

举例

    def popitem(self): # real signature unknown; restored from __doc__
        """
        D.popitem() -> (k, v), remove and return some (key, value) pair as a
        2-tuple; but raise KeyError if D is empty.
        """
        pass

popitem

#9.增加，如果存在,不做操作

# name = {
#     'name':'alex',
#     'age':23,
#     'gender':'女'
# }
# #name.setdefault('name','alex')
# name.setdefault('love','none')
# print(name)

举例

    def setdefault(self, k, d=None): # real signature unknown; restored from __doc__
        """ D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D """
        pass

setdefault

#10.批量增加或修改

# name = {
#     'name':'alex',
#     'age':23,
#     'gender':'女'
# }
# v = {
#     'k1':'v1',
#     'k2':'v2'
# }
# #name.update({'love':'none','aihao':'sleep'})
# name.update(v)
# print(name)

举例

    def update(self, E=None, **F): # known special case of dict.update
        """
        D.update([E, ]**F) -> None.  Update D from dict/iterable E and F.
        If E is present and has a .keys() method, then does:  for k in E: D[k] = E[k]
        If E is present and lacks a .keys() method, then does:  for k, v in E: D[k] = v
        In either case, this is followed by: for k in F:  D[k] = F[k]
        """
        pass

update

#11.接受一个可循环的东西，创建字典

#@staticmethod 脑袋上顶了这个的，就比较特殊，要使用dict.调用  静态方法
# dic = dict.fromkeys(['k1','k2','k3'],123)
# print(dic)
# #打印结果
# #{'k1': 123, 'k2': 123, 'k3': 123}#创建了一个字典，value都一样，也只能一样
# dic['k1'] = 'alex'
# print(dic)
# #打印结果
# #{'k1': 'alex', 'k2': 123, 'k3': 123}
#
# dic1 = dict.fromkeys(['k1','k2','k3'],[1,])
# print(dic1)
# #打印结果
# #{'k1': [1], 'k2': [1], 'k3': [1]}
# dic1['k1'].append('222')
# print(dic1)
# #打印结果
# #{'k1': [1, '222'], 'k2': [1, '222'], 'k3': [1, '222']}
# dic1['k1'].remove('222')
# print(dic1)
# #打印结果
# #{'k1': [1], 'k2': [1], 'k3': [1]}

举例

# #观察打印结果，配合着下图理解

@staticmethod # known case
    def fromkeys(*args, **kwargs): # real signature unknown
        """ Returns a new dict with keys from iterable and values equal to value. """
        pass

fromkeys

#12.相互嵌套

# students_info = {
#     '张三': '好学生',
#     '李四': {'English_name': 'lisi', 'age': 28, 'gender': 'boy'},
#     '王五': {'alse': 'wangwu', 'age': 52, '后宫': ['甄嬛', '华妃', '皇后']}
# }
# print(students_info)

#相互嵌套的添加内容
# 把列表和字典单独的基本操作熟练了，这个混合的就好处理些
# students_info = {
#     '张三': '好学生',
#     '李四': {'English_name': 'lisi', 'age': 28, 'gender': 'boy'},
#     '王五': {'alse': 'wangwu', 'age': 52, '后宫': ['甄嬛', '华妃', '皇后']},
#     '赵六': ['alex', 'eric', ['a', 'b', 'c'], '李杰', {'k11': 'vv1'}],
# }
# 增加
#students_info['赵六'][2].append('d')

# print(students_info)
# 修改
# students_info['赵六'][4]['age'] = '我没有年龄'
# print(students_info)

#实例：
# user_list = [
#     {'name': 'alex', 'password': '123'},
#     {'name': 'blex', 'password': '123'},
#     {'name': 'clex', 'password': '123'}
# ]
# print(user_list)
# user = input('用户名：')
# pwd = input('密码：')
# for item in user_list:
#     if user == item['name'] and pwd == item['password']:
#         print('登录成功!')
#         break
#     else:
#         print("滚！！！")

举例

##13.额外重点
#字典的key
# 1.是不可变类型 元组是不可变类型  元组里套列表就不行了，列表是可变类型
# 2. TRUE和1 可以做key  但是每次选其一 否则会重复

# dic = {
#     'k1': 'v1',
#     'k2': [1,2,3,],
#     (1,2): 'lllll',
#     1: 'fffffffff',
#     111: 'asdf',
# }
# print(dic)

举例