Python学习笔记_基础篇(五)_数据类型之字典

一.基本数据类型
整数：int
字符串：str(注：\t等于一个tab键)
布尔值： bool
列表：list
列表用[]
元祖：tuple
元祖用（）
字典：dict

注：所有的数据类型都存在想对应的类列里，元祖和列表功能一样，列表可以修改，元祖不能修改。

二.字典所有数据类型：

常用操作：

• 索引
• 新增
• 删除
• 键、值、键值对
• 循环
• 长度

class dict(object):"""dict() -> new empty dictionarydict(mapping) -> new dictionary initialized from a mapping object's(key, value) pairsdict(iterable) -> new dictionary initialized as if via:d = {}for k, v in iterable:d[k] = vdict(**kwargs) -> new dictionary initialized with the name=value pairsin the keyword argument list.  For example:  dict(one=1, two=2)"""def clear(self): # real signature unknown; restored from __doc__""" D.clear() -> None.  Remove all items from D. """passdef copy(self): # real signature unknown; restored from __doc__""" D.copy() -> a shallow copy of D """pass@staticmethod # known casedef fromkeys(*args, **kwargs): # real signature unknown""" Returns a new dict with keys from iterable and values equal to value. """passdef 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. """passdef items(self): # real signature unknown; restored from __doc__""" D.items() -> a set-like object providing a view on D's items """passdef keys(self): # real signature unknown; restored from __doc__""" D.keys() -> a set-like object providing a view on D's keys """passdef 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"""passdef popitem(self): # real signature unknown; restored from __doc__"""D.popitem() -> (k, v), remove and return some (key, value) pair as a2-tuple; but raise KeyError if D is empty."""passdef 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 """passdef 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] = vIn either case, this is followed by: for k in F:  D[k] = F[k]"""passdef values(self): # real signature unknown; restored from __doc__""" D.values() -> an object providing a view on D's values """passdef __contains__(self, *args, **kwargs): # real signature unknown""" True if D has a key k, else False. """passdef __delitem__(self, *args, **kwargs): # real signature unknown""" Delete self[key]. """passdef __eq__(self, *args, **kwargs): # real signature unknown""" Return self==value. """passdef __getattribute__(self, *args, **kwargs): # real signature unknown""" Return getattr(self, name). """passdef __getitem__(self, y): # real signature unknown; restored from __doc__""" x.__getitem__(y) <==> x[y] """passdef __ge__(self, *args, **kwargs): # real signature unknown""" Return self>=value. """passdef __gt__(self, *args, **kwargs): # real signature unknown""" Return self>value. """passdef __init__(self, seq=None, **kwargs): # known special case of dict.__init__"""dict() -> new empty dictionarydict(mapping) -> new dictionary initialized from a mapping object's(key, value) pairsdict(iterable) -> new dictionary initialized as if via:d = {}for k, v in iterable:d[k] = vdict(**kwargs) -> new dictionary initialized with the name=value pairsin the keyword argument list.  For example:  dict(one=1, two=2)# (copied from class doc)"""passdef __iter__(self, *args, **kwargs): # real signature unknown""" Implement iter(self). """passdef __len__(self, *args, **kwargs): # real signature unknown""" Return len(self). """passdef __le__(self, *args, **kwargs): # real signature unknown""" Return self<=value. """passdef __lt__(self, *args, **kwargs): # real signature unknown""" Return self<value. """pass@staticmethod # known case of __new__def __new__(*args, **kwargs): # real signature unknown""" Create and return a new object.  See help(type) for accurate signature. """passdef __ne__(self, *args, **kwargs): # real signature unknown""" Return self!=value. """passdef __repr__(self, *args, **kwargs): # real signature unknown""" Return repr(self). """passdef __setitem__(self, *args, **kwargs): # real signature unknown""" Set self[key] to value. """passdef __sizeof__(self): # real signature unknown; restored from __doc__""" D.__sizeof__() -> size of D in memory, in bytes """pass__hash__ = None

dict

三.所有字典数据类型举例

user_info = {0 :"zhangyanlin","age"  :"18",2  :"pythoner"
}
#获取所有的key
print(user_info.keys())#获取所有的values
print(user_info.values())#获取所有的key和values
print(user_info.items())clear清除所有的内容
user_info.clear()
print(user_info)#get 根据key获取值，如果key不存在，可以指定一个默认值
val = user_info.get('age')
print(val)#update批量更新
test = {'a':111,'b':222
}
user_info.update(test)
print(user_info)

四.索引

#如果没有key，会报错
user_info = {"name" :'zhangyanlin',"age"  :18,"job"  :'pythoner'
}
print(user_info['name'])

五.for循环

#循环
user_info = {0 :"zhangyanlin","age"  :"18",2  :"pythoner"
}
for i in user_info:print(i)#循环输出所有的键入值
for k,v in user_info.items():print(k)print(v)