$ ipython
Python 3.7.3(default, Mar 282019,10:38:38)[MSC v.191532 bit (Intel)]
Type 'copyright','credits'or'license'for more information
IPython 7.4.0-- An enhanced Interactive Python. Type '?'forhelp.
In [1]: user_tuple =('laoliu',30,175,'beijing')# python的拆包特性
In [2]: name,*other = user_tuple
In [3]: name
Out[3]:'laoliu'
In [4]: other
Out[4]:[30,175,'beijing']# 拆包
In [5]: name, age, hight, address = user_tuple
In [6]:print(name, age, hight, address)
laoliu 30175 beijing
In [7]: d ={}# 元組可以作爲dict的鍵, 但list不可以,這是因爲tuple是不可變對象
In [8]: d[user_tuple]='shanghai'
In [9]: d
Out[9]:{('laoliu',30,175,'beijing'):'shanghai'}
namedtuple的使用方法示例
Python 3.7.3(default, Mar 282019,10:38:38)[MSC v.191532 bit (Intel)]
Type 'copyright','credits'or'license'for more information
IPython 7.4.0-- An enhanced Interactive Python. Type '?'forhelp.
In [1]:from collections import namedtuple
In [2]: User = namedtuple("User",['name','age'])
In [3]: user = User(name='liu',age=18)
In [4]:print(user.name, user.age)
liu 18
In [5]: user_tuple =('zhang',19)# 以 * 傳參, 也是位置參數, 詳解可參照函數的傳參方式
In [6]: user2 = User(*user_tuple)
In [7]:print(user.name, user.age)
liu 18
In [8]:print(user2.name, user2.age)
zhang 19
In [9]: user_dict ={'name':'wang','age':20}# 以 ** 傳參, 也就是關鍵字參數, 詳解可參照函數的傳參方式
In [10]: user3 = User(**user_dict)
In [11]:print(user3.name, user3.age)
wang 20# 新增屬性之後的解決辦法
In [12]: User = namedtuple('User',['name','age','height'])
In [13]: user = User(name='liu',age=18)---------------------------------------------------------------------------
TypeError Traceback (most recent call last)<ipython-input-13-7d01a0548062>in<module>---->1 user = User(name='liu',age=18)
TypeError: __new__() missing 1 required positional argument:'height'# 第一種解決辦法就是添加關鍵字
In [14]: user = User(name='liu',age=18, height=170)
In [15]:print(user.name, user.age, user.height)
liu 18170
In [16]:print(user2.name, user2.age, user2.height)---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)<ipython-input-16-d9f0ea18d8bf>in<module>---->1print(user2.name, user2.age, user2.height)
AttributeError:'User'object has no attribute 'height'
In [17]: user2
Out[17]: User(name='zhang', age=19)# 這個就是函數傳參中的位置參數與關鍵字參數混用的例子
In [18]: user2 = User(*user_tuple, height=171)
In [19]: user2
Out[19]: User(name='zhang', age=19, height=171)
In [20]: user3
Out[20]: User(name='wang', age=20)# 錯誤傳參示例
In [21]: use3 = User(**user_dict,'height':172)
File "<ipython-input-22-9441aec8cf18>", line 1
use3 = User(**user_dict,'height':172)^
SyntaxError: invalid syntax
# 錯誤傳參示例
In [22]: use3 = User(**user_dict,{'height':172})
File "<ipython-input-23-55ac47e668b6>", line 1
use3 = User(**user_dict,{'height':172})^
SyntaxError: positional argument follows keyword argument unpacking
In [23]: user_dict
Out[23]:{'name':'wang','age':20}
In [24]: user_dict.update({'height':172})
In [25]: user_dict
Out[25]:{'name':'wang','age':20,'height':172}
In [26]: user3 = User(**user_dict)
In [27]: user3
Out[27]: User(name='wang', age=20, height=172)
defaultdict 使用詳解
Python 3.7.3(default, Mar 282019,10:38:38)[MSC v.191532 bit (Intel)]
Type 'copyright','credits'or'license'for more information
IPython 7.4.0-- An enhanced Interactive Python. Type '?'forhelp.
In [1]:from collections import defaultdict
In [2]: users =['liu1','liu2','liu3','liu1','liu1','liu2']
In [3]:# 統計users中每個名字出現的次數
In [4]: user_dict ={}# 這是我們常用的方法來解決
In [5]:for user in users:...:if user in user_dict:...: user_dict[user]+=1...:else:...: user_dict[user]=1...:
In [6]: user_dict # 結果
Out[6]:{'liu1':3,'liu2':2,'liu3':1}# 第二種解決辦法, 使用setdefault()
In [7]: user_dict2 ={}
In [8]:for user in users:...: user_dict2.setdefault(user,0)...: user_dict2[user]+=1...:
In [9]: user_dict2
Out[9]:{'liu1':3,'liu2':2,'liu3':1}# 第三種解決辦法 使用defaultdict() (推薦使用)
In [10]: user_dict3 = defaultdict(int)
In [11]:for user in users:...: user_dict3[user]+=1...:
In [12]: user_dict3
Out[12]: defaultdict(int,{'liu1':3,'liu2':2,'liu3':1})# defaultdict() 擴展使用, 創建一些複雜的數據結構# 求如下數據結構:{'group1':{'name':'','nums':0}}
In [13]:defgen_default():...:return{'name':'','nums':0}...:
In [14]: default_dict = defaultdict(gen_default)
In [15]: default_dict['group1']
Out[15]:{'name':'','nums':0}
deque 使用詳解
deque 是線程安全的, list是非線程安全的,在多線程編程的情況下要多注意
queue (隊列)其實是deque實現在的
deque是使用C語言編寫的, 速度很快, 可以經常使用
Python 3.7.3(default, Mar 282019,10:38:38)[MSC v.191532 bit (Intel)]
Type 'copyright','credits'or'license'for more information
IPython 7.4.0-- An enhanced Interactive Python. Type '?'forhelp.
In [1]:from collections import deque
In [2]: a =['b','c','d']# 將list轉爲deque
In [3]: a_duque = deque(a)
In [4]: a_duque
Out[4]: deque(['b','c','d'])# 將tuple轉爲deque
In [5]: b =(1,2,3)
In [6]: b_duque = deque(b)
In [7]: b_duque
Out[7]: deque([1,2,3])
In [8]: c ={"a":1,"b":2,"c":4}# 將dice轉爲deque
In [9]: c_deque = deque(c)
In [10]: c_deque
Out[10]: deque(['a','b','c'])# deque的append操作,同list
In [11]: c_deque.append('d')
In [12]: c_deque
Out[12]: deque(['a','b','c','d'])# deque.appendleft() 將元素添加至左側第0個位置
In [13]: c_deque.appendleft('e')
In [14]: c_deque
Out[14]: deque(['e','a','b','c','d'])# 淺拷貝
In [15]: c_deque_copy = c_deque.copy()
In [16]: c_deque_copy.count()---------------------------------------------------------------------------
TypeError Traceback (most recent call last)<ipython-input-16-6cfcef3ac009>in<module>---->1 c_deque_copy.count()
TypeError: count() takes exactly one argument (0 given)# 查找某個元素的出現的次數
In [17]: c_deque_copy.count('a')
Out[17]:1
In [18]: c_deque_copy
Out[18]: deque(['e','a','b','c','d'])
In [19]: c_deque_copy[1]='a1'
In [20]: c_deque_copy
Out[20]: deque(['e','a1','b','c','d'])
In [21]: c_deque
Out[21]: deque(['e','a','b','c','d'])# 合併兩個deque, 將後者deque合併至前者的右側,原址修改,返回None
In [22]: c_deque.extend(a_duque)
In [23]: c_deque
Out[23]: deque(['e','a','b','c','d','b','c','d'])# 合併兩個deque, 將全者的deque合併至前者的左側, 原地修改, 返回None
In [24]: c_deque.extendleft(b_duque)
In [25]: c_deque
Out[25]: deque([3,2,1,'e','a','b','c','d','b','c','d'])# 返回元素的索引位置
In [26]: c_deque.index('b')
Out[26]:5# 在給出的位置插入元素
In [27]: c_deque.insert(2,'f')
In [28]: c_deque
Out[28]: deque([3,2,'f',1,'e','a','b','c','d','b','c','d'])
In [29]: c_deque.rotate('a')---------------------------------------------------------------------------
TypeError Traceback (most recent call last)<ipython-input-29-fc907ea6932a>in<module>---->1 c_deque.rotate('a')
TypeError:'str'object cannot be interpreted as an integer
# 將隊尾的指定數量的元素放到隊前, 默認爲1
In [30]: c_deque.rotate()
In [31]: c_deque
Out[31]: deque(['d',3,2,'f',1,'e','a','b','c','d','b','c'])# 反轉整個deque
In [32]: c_deque.reverse()
In [33]: c_deque
Out[33]: deque(['c','b','d','c','b','a','e',1,'f',2,3,'d'])
In [34]:
Counter 使用詳解
Python 3.7.3(default, Mar 282019,10:38:38)[MSC v.191532 bit (Intel)]
Type 'copyright','credits'or'license'for more information
IPython 7.4.0-- An enhanced Interactive Python. Type '?'forhelp.
In [1]:from collections import Counter
In [2]: users =['liu1','liu2','liu3','liu1','liu1','liu2']# 對列表中的數據進行統計
In [3]: users_counter = Counter(users)
In [4]: users_counter
Out[4]: Counter({'liu1':3,'liu2':2,'liu3':1})# 統計字符中,每個字符出現的次數
In [5]: test = Counter('abcddfdefadsfasdjfoaisdfjasdjfasdfasdfasdfgfhdf')
In [6]: test
Out[6]:
Counter({'a':8,'b':1,'c':1,'d':11,'f':11,'e':1,'s':7,'j':3,'o':1,'i':1,'g':1,'h':1})# 統計兩個字符串中的字符出現次數, 方法1
In [7]: test.update('aadfd')
In [8]: test
Out[8]:
Counter({'a':10,'b':1,'c':1,'d':13,'f':12,'e':1,'s':7,'j':3,'o':1,'i':1,'g':1,'h':1})# 統計兩個字符串中的字符出現次數, 方法2
In [9]: test2 = Counter('abcde')
In [10]: test.update(test2)
In [11]: test
Out[11]:
Counter({'a':11,'b':2,'c':2,'d':14,'f':12,'e':2,'s':7,'j':3,'o':1,'i':1,'g':1,'h':1})# TOP n 的統計方法
In [12]: test.most_common(3)
Out[12]:[('d',14),('f',12),('a',11)]
OrderedDict 使用詳解
Python 3.7.3(default, Mar 282019,10:38:38)[MSC v.191532 bit (Intel)]
Type 'copyright','credits'or'license'for more information
IPython 7.4.0-- An enhanced Interactive Python. Type '?'forhelp.
In [1]:from collections import OrderedDict
In [2]: user_dict = OrderedDict()
In [3]: user_dict['b']='liu'
In [4]: user_dict['a']='liu1'
In [5]: user_dict['c']='liu2'
In [6]: user_dict
Out[6]: OrderedDict([('b','liu'),('a','liu1'),('c','liu2')])# 彈出最後一個item.
In [7]: user_dict.popitem()
Out[7]:('c','liu2')
In [8]: user_dict
Out[8]: OrderedDict([('b','liu'),('a','liu1')])# 移動元素至最後 使用場景優先級
In [9]: user_dict.move_to_end('b')
In [10]: user_dict
Out[10]: OrderedDict([('a','liu1'),('b','liu')])# 彈出最後一個key,返回key對應的值
In [11]: user_dict.pop('b')
Out[11]:'liu'
In [12]: user_dict
Out[12]: OrderedDict([('a','liu1')])
ChainMap 使用詳解
Python 3.7.3(default, Mar 282019,10:38:38)[MSC v.191532 bit (Intel)]
Type 'copyright','credits'or'license'for more information
IPython 7.4.0-- An enhanced Interactive Python. Type '?'forhelp.
In [1]:from collections import ChainMap
In [2]: dict1 ={'a':'liu','b':"liu1"}
In [3]: dict2 ={"c":"liu3",'d':'liu4'}# 最常使用的方法就是連接多個dict, 若鍵重複, 則只取第一個dict中的鍵值
In [4]: new_dict = ChainMap(dict1, dict2)
In [5]:for key, value in new_dict.items():...:print(key, value)...:
c liu3
d liu4
a liu
b liu1
# 修改dict2, 使其中一個鍵與dict1的鍵重複
In [6]: dict2 ={"b":"liu3",'d':'liu4'}
In [7]: new_dict = ChainMap(dict1, dict2)
In [8]:for key, value in new_dict.items():...:print(key, value)...:
b liu1
d liu4
a liu
In [9]: new_dict
Out[9]: ChainMap({'a':'liu','b':'liu1'},{'b':'liu3','d':'liu4'})# 返回dict的list, 但只是指向原來dict, 不是原dict的copy
In [10]: new_dict.maps
Out[10]:[{'a':'liu','b':'liu1'},{'b':'liu3','d':'liu4'}]
In [11]: new_dict.maps[0]['a']='liu333'
In [12]: new_dict
Out[12]: ChainMap({'a':'liu333','b':'liu1'},{'b':'liu3','d':'liu4'})
In [13]: dict1
Out[13]:{'a':'liu333','b':'liu1'}
