Python数据类型详解（四）字典：dict

class dict(object):
  """
  dict() -> new empty dictionary
  dict(mapping) -> new dictionary initialized from a mapping object's
    (key, value) pairs
  dict(iterable) -> new dictionary initialized as if via:
    d = {}
    for k, v in iterable:
      d[k] = v
  dict(**kwargs) -> new dictionary initialized with the name=value pairs
    in 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. """
    pass

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

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

  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

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

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

  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

  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

  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

  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

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

  def __contains__(self, *args, **kwargs): # real signature unknown
    """ True if D has a key k, else False. """
    pass

  def __delitem__(self, *args, **kwargs): # real signature unknown
    """ Delete self[key]. """
    pass

  def __eq__(self, *args, **kwargs): # real signature unknown
    """ Return self==value. """
    pass

  def __getattribute__(self, *args, **kwargs): # real signature unknown
    """ Return getattr(self, name). """
    pass

  def __getitem__(self, y): # real signature unknown; restored from __doc__
    """ x.__getitem__(y) <==> x[y] """
    pass

  def __ge__(self, *args, **kwargs): # real signature unknown
    """ Return self>=value. """
    pass

  def __gt__(self, *args, **kwargs): # real signature unknown
    """ Return self>value. """
    pass

  def __init__(self, seq=None, **kwargs): # known special case of dict.__init__
    """
    dict() -> new empty dictionary
    dict(mapping) -> new dictionary initialized from a mapping object's
      (key, value) pairs
    dict(iterable) -> new dictionary initialized as if via:
      d = {}
      for k, v in iterable:
        d[k] = v
    dict(**kwargs) -> new dictionary initialized with the name=value pairs
      in the keyword argument list. For example: dict(one=1, two=2)
    # (copied from class doc)
    """
    pass

  def __iter__(self, *args, **kwargs): # real signature unknown
    """ Implement iter(self). """
    pass

  def __len__(self, *args, **kwargs): # real signature unknown
    """ Return len(self). """
    pass

  def __le__(self, *args, **kwargs): # real signature unknown
    """ Return self<=value. """
    pass

  def __lt__(self, *args, **kwargs): # real signature unknown
    """ Return self size of D in memory, in bytes """
    pass

  __hash__ = None

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)

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

#循环
user_info = {
  0 :"zhangyanlin",
  "age" :"18",
  2 :"pythoner"
}
for i in user_info:
  print(i)
 
#循环