Dict 数据类型
一、创建一个字典
>>> a = {'name': 'gm', 'age': 18}
>>> a
{'age': 18, 'name': 'gm'}
二、查看字典
# 获取字典a的值
>>> a
{'age': 18, 'name': 'gm'}
# 获取特定key的值
>>> a.['name']'gm'
>>> a.['age']18
三、查看列表可进行的操作
>>> dir(a)
['clear', 'copy', 'fromkeys', 'get', 'items', 'keys', 'pop', 'popitem', 'setdefault', 'update', 'values']
dict 函数方法
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
""" Create a new dictionary with keys from iterable and values set to value. """
pass
def get(self, *args, **kwargs): # real signature unknown
""" Return the value for key if key is in the dictionary, else default. """
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 the key is not found, return the default if given; otherwise,
raise a KeyError.
"""
pass
def popitem(self, *args, **kwargs): # real signature unknown
"""
Remove and return a (key, value) pair as a 2-tuple.
Pairs are returned in LIFO (last-in, first-out) order.
Raises KeyError if the dict is empty.
"""
pass
def setdefault(self, *args, **kwargs): # real signature unknown
"""
Insert key with a value of default if key is not in the dictionary.
Return the value for key if key is in the dictionary, else default.
"""
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 __class_getitem__(self, *args, **kwargs): # real signature unknown
""" See PEP 585 """
pass
def __contains__(self, *args, **kwargs): # real signature unknown
""" True if the dictionary has the specified key, 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 __ior__(self, *args, **kwargs): # real signature unknown
""" Return self|=value. """
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<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. """
pass
def __ne__(self, *args, **kwargs): # real signature unknown
""" Return self!=value. """
pass
def __or__(self, *args, **kwargs): # real signature unknown
""" Return self|value. """
pass
def __repr__(self, *args, **kwargs): # real signature unknown
""" Return repr(self). """
pass
def __reversed__(self, *args, **kwargs): # real signature unknown
""" Return a reverse iterator over the dict keys. """
pass
def __ror__(self, *args, **kwargs): # real signature unknown
""" Return value|self. """
pass
def __setitem__(self, *args, **kwargs): # real signature unknown
""" Set self[key] to value. """
pass
def __sizeof__(self): # real signature unknown; restored from __doc__
""" D.__sizeof__() -> size of D in memory, in bytes """
pass
__hash__ = None
四、常用的字典操作
# 插入新的键值
>>> a
{'age': 18, 'name': 'gm'}
>>> a['job'] = '运维'
>>> a
{'age': 18, 'job': '运维', 'name': 'gm'}
# 修改字典某键的值
>>> a
{'age': 18, 'name': 'gm'}
>>> a['name']='root'
>>> a
{'age': 18, 'name': 'root'}
# 获取字典某元素的值
>>> a
{'age': 18, 'job': '运维', 'name': 'gm'}
>>> a['gender']
Traceback (most recent call last):
File "<pyshell#51>", line 1, in <module>
a['gender']
KeyError: 'gender'
>>> a.get('gender')
>>> a.get('gender',-1)
-1
>>> a.get('name',-1)
'gm'
# 删除字典某元素
>>> a
{'age': 18, 'job': '运维', 'name': 'gm'}
>>> a.pop('job')
'运维'
>>> a
{'age': 18, 'name': 'gm'}
# 获取字典删除的元素的值
>>> a
{'age': 18, 'job': '运维', 'name': 'gm'}
>>> c = a.pop('job')
>>> c
'运维'
>>> a
{'age': 18, 'name': 'gm'}
- keys()、values()、items()方法
# Python3中字典的keys()、values()、items()方法的区别
>>> a.keys() # 以列表返回字典所有的键
dict_keys(['age', 'job', 'name'])
>>> a.values() # 以列表返回字典中的所有值
dict_values([18, '运维', 'gm'])
>>> a.items() # 以列表返回字典可遍历的(键, 值) 元组数组
dict_items([('age', 18), ('job', '运维'), ('name', 'gm')])
五、字典练习
有如下值集合 [11,22,33,44,55,66,77,88,99,90...]，
将所有大于 66 的值保存至字典的第一个key中，
将小于 66 的值保存至第二个key的值中。
即： {'k1': 大于66 , 'k2': 小于66}
b = {}
a = [11, 22, 33, 44, 55, 66, 77, 88, 99, 90, ]
for i in a:
if i > 66:
if 'k1' in b.keys():
b['k1'].append(i)
else:
b['k1']= [i, ]
else:
if 'k2' in b.keys():
b['k2'].append(i)
else:
b['k2']= [i, ]
print(b)
print(b['k1'])
print(b['k2'])
{'k2': [11, 22, 33, 44, 55, 66], 'k1': [77, 88, 99, 90]}
[77, 88, 99, 90]
[11, 22, 33, 44, 55, 66]
