Python錯誤匯總，python匯總

Python錯誤匯總，python匯總

開個貼，用於記錄平時經常碰到的Python的錯誤同時對導致錯誤的原因進行分析，並持續更新，方便以後查詢，學習。

知識在於積累嘛！

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In [105]: T1 = (1)In [106]: T2 = (2,3)In [107]: T1 + T2---------------------------------------------------------------------------TypeError                                 Traceback (most recent call last)<ipython-input-107-b105c7b32d90> in <module>()----> 1 T1 + T2;TypeError: unsupported operand type(s) for +: 'int' and 'tuple'

【錯誤分析】(1)的類型是整數，所以不能與另一個元祖做合併作業，如果只有一個元素的元祖，應該用 (1 , )來表示

In [108]: type(T1)Out[108]: intIn [109]: T1 = (1,)In [110]: T2 = (2,3)In [111]: T1 + T2Out[111]: (1, 2, 3)

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>>> hash(1,(2,[3,4]))Traceback (most recent call last):  File "<pyshell#95>", line 1, in <module>    hash((1,2,(2,[3,4])))TypeError: unhashable type: 'list'

【錯誤分析】字典中的鍵必須是不可變對象，如(整數，浮點數，字串，元祖)，可用hash()判斷某個對象是否可雜湊

>>> hash('string')-1542666171

但列表中元素是可變對象，所以是不可雜湊的，所以會報上面的錯誤.如果要用列表作為字典中的鍵，最簡單的辦法是:

>>> D = {}>>> D[tuple([3,4])] = 5>>> D{(3, 4): 5}

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>>> L = [2,1,4,3]>>> L.reverse().sort()Traceback (most recent call last):  File "<stdin>", line 1, in <module>AttributeError: 'NoneType' object has no attribute 'sort'>>> L[3, 4, 1, 2]

【錯誤分析】列表屬於可變對象,其append(),sort(),reverse()會在原處修改對象，不會有返回值，或者說返回值為空白，
所以要實現反轉並排序，不能並行操作，要分開來寫

>>> L = [2,1,4,3]>>> L.reverse()>>> L.sort()>>> L[1, 2, 3, 4]

或者用下面的方法實現:

In [103]: sorted(reversed([2,1,4,3]))Out[103]: [1, 2, 3, 4]

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>>> class = 78SyntaxError: invalid syntax

【錯誤分析】class是Python保留字，Python保留字不能做變數名，可以用Class，或klass
同樣，保留字不能作為模組名來匯入，比如說，有個and.py，但不能將其作為模組匯入

>>> import andSyntaxError: invalid syntax

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>>> f = open('D:\new\text.data','r')Traceback (most recent call last):  File "<stdin>", line 1, in <module>IOError: [Errno 22] invalid mode ('r') or filename: 'D:\new\text.data'>>> f = open(r'D:\new\text.data','r')>>> f.read()'Very\ngood\naaaaa'

【錯誤分析】\n預設為換行，\t預設為TAB鍵，所以在D:\目錄下找不到ew目錄下的ext.data檔案，將其改為raw方式輸入即可。
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try:    print 1 / 0    except ZeroDivisionError:    print 'integer division or modulo by zero'    finally:    print 'Done'else:      print 'Continue Handle other part'報錯如下:D:\>python Learn.py  File "Learn.py", line 11    else:       ^SyntaxError: invalid syntax

【錯誤分析】錯誤原因，else, finally執行位置;正確的程式應該如下:

try:    print 1 / 0    except ZeroDivisionError:    print 'integer division or modulo by zero'else:      print 'Continue Handle other part'    finally:    print 'Done'

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>>> [x,y for x in range(2) for y in range(3)]  File "<stdin>", line 1    [x,y for x in range(2) for y in range(3)]           ^SyntaxError: invalid syntax

【錯誤分析】錯誤原因，列表解析中，x,y必須以數組的方式列出(x,y)

>>> [(x,y) for x in range(2) for y in range(3)][(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2)]

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class JustCounter:    __secretCount = 0    def count(self):        self.__secretCount += 1        print 'secretCount is:', self.__secretCountcount1 = JustCounter()count1.count()count1.count()count1.__secretCount

報錯如下:

>>> secretCount is: 1secretCount is: 2Traceback (most recent call last):  File "D:\Learn\Python\Learn.py", line 13, in <module>    count1.__secretCountAttributeError: JustCounter instance has no attribute '__secretCount'    

【錯誤分析】雙底線的類屬性__secretCount不可訪問，所以會報無此屬性的錯誤. 

解決辦法如下:

# 1. 可以通過其內部成員方法訪問# 2. 也可以通過訪問ClassName._ClassName__Attr#或 ClassInstance._ClassName__Attr#來訪問，比如：print count1._JustCounter__secretCountprint JustCounter._JustCounter__secretCount 

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>>> print xTraceback (most recent call last):  File "<stdin>", line 1, in <module>NameError: name 'x' is not defined>>> x = 1>>> print x1

【錯誤分析】Python不允許使用未賦值變數
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>>> t = (1,2)>>> t.append(3)Traceback (most recent call last):  File "<stdin>", line 1, in <module>AttributeError: 'tuple' object has no attribute 'append'>>> t.remove(2)Traceback (most recent call last):  File "<stdin>", line 1, in <module>AttributeError: 'tuple' object has no attribute 'remove'>>> t.pop()Traceback (most recent call last):  File "<stdin>", line 1, in <module>AttributeError: 'tuple' object has no attribute 'pop'

【錯誤分析】屬性錯誤,歸根到底在於元祖是不可變類型，所以沒有這幾種方法.
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>>> t = ()>>> t[0]Traceback (most recent call last):  File "<stdin>", line 1, in <module>IndexError: tuple index out of range>>> l = []>>> l[0]Traceback (most recent call last):  File "<stdin>", line 1, in <module>IndexError: list index out of range

【錯誤分析】空元祖和空列表，沒有索引為0的項
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>>> if X>Y:...  X,Y = 3,4...   print X,Y  File "<stdin>", line 3    print X,Y    ^IndentationError: unexpected indent>>>   t = (1,2,3,4)  File "<stdin>", line 1    t = (1,2,3,4)    ^IndentationError: unexpected indent

【錯誤分析】一般出在代碼縮排的問題
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>>> f = file('1.txt')>>> f.readline()'AAAAA\n'>>> f.readline()'BBBBB\n'>>> f.next()'CCCCC\n'

【錯誤分析】如果檔案裡面沒有行了會報這種異常

>>> f.next() #Traceback (most recent call last):  File "<stdin>", line 1, in <module>StopIteration

有可迭代的對象的next方法,會前進到下一個結果,而在一系列結果的末尾時,會引發StopIteration的異常.

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>>> string = 'SPAM'>>> a,b,c = stringTraceback (most recent call last):  File "<stdin>", line 1, in <module>ValueError: too many values to unpack

【錯誤分析】接受的變數少了，應該是

>>> a,b,c,d = string>>> a,d('S', 'M')#除非用切片的方式>>> a,b,c = string[0],string[1],string[2:]>>> a,b,c('S', 'P', 'AM')或者>>> a,b,c = list(string[:2]) + [string[2:]]>>> a,b,c('S', 'P', 'AM')或者>>> (a,b),c = string[:2],string[2:]>>> a,b,c('S', 'P', 'AM')或者>>> ((a,b),c) = ('SP','AM')>>> a,b,c('S', 'P', 'AM')簡單點就是:>>> a,b = string[:2]>>> c   = string[2:]>>> a,b,c('S', 'P', 'AM')

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>>> mydic={'a':1,'b':2}>>> mydic['a']1>>> mydic['c']Traceback (most recent call last):  File "<stdin>", line 1, in ?KeyError: 'c'

【錯誤分析】當映射到字典中的鍵不存在時候，就會觸發此類異常, 或者可以，這樣測試

>>> 'a' in mydic.keys()True>>> 'c' in mydic.keys()              #用in做成員歸屬測試False>>> D.get('c','"c" is not exist!')   #用get或擷取鍵，如不存在，會列印後面給出的錯誤資訊'"c" is not exist!'

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  File "study.py", line 3    return None    ^IndentationError: unexpected indent

【錯誤分析】一般是代碼縮排問題，TAB鍵或空格鍵不一致導致

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>>>def A():return A()>>>A() #無限迴圈，等消耗掉所有記憶體資源後，報最大遞迴深度的錯誤  File "<pyshell#2>", line 2, in A return A()RuntimeError: maximum recursion depth exceededclass Bird:    def __init__(self):        self.hungry = True    def eat(self):        if self.hungry:            print "Ahaha..."            self.hungry = False        else:            print "No, Thanks!"該類定義鳥的準系統吃，吃飽了就不再吃輸出結果:>>> b = Bird()>>> b.eat()Ahaha...>>> b.eat()No, Thanks!下面一個子類SingBird,class SingBird(Bird):    def __init__(self):        self.sound = 'squawk'    def sing(self):        print self.sound輸出結果:>>> s = SingBird()>>> s.sing()squawkSingBird是Bird的子類，但如果調用Bird類的eat()方法時,>>> s.eat()Traceback (most recent call last):  File "<pyshell#5>", line 1, in <module>    s.eat()  File "D:\Learn\Python\Person.py", line 42, in eat    if self.hungry:AttributeError: SingBird instance has no attribute 'hungry'

【錯誤分析】代碼錯誤很清晰,SingBird中初始化代碼被重寫，但沒有任何初始化hungry的代碼

class SingBird(Bird):    def __init__(self):        self.sound = 'squawk'        self.hungry = Ture #加這麼一句    def sing(self):        print self.sound

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class Bird:    def __init__(self):        self.hungry = True    def eat(self):        if self.hungry:            print "Ahaha..."            self.hungry = False        else:            print "No, Thanks!"class SingBird(Bird):    def __init__(self):        super(SingBird,self).__init__()        self.sound = 'squawk'    def sing(self):        print self.sound>>> sb = SingBird()Traceback (most recent call last):  File "<pyshell#5>", line 1, in <module>    sb = SingBird()  File "D:\Learn\Python\Person.py", line 51, in __init__    super(SingBird,self).__init__()TypeError: must be type, not classobj

【錯誤分析】在模組首行裡面加上__metaclass__=type，具體還沒搞清楚為什麼要加

__metaclass__=typeclass Bird:    def __init__(self):        self.hungry = True    def eat(self):        if self.hungry:            print "Ahaha..."            self.hungry = False        else:            print "No, Thanks!"class SingBird(Bird):    def __init__(self):        super(SingBird,self).__init__()        self.sound = 'squawk'    def sing(self):        print self.sound>>> S = SingBird()>>> S.SyntaxError: invalid syntax>>> S.SyntaxError: invalid syntax>>> S.eat()Ahaha...

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>>> T(1, 2, 3, 4)>>> T[0] = 22 Traceback (most recent call last):  File "<pyshell#129>", line 1, in <module>    T[0] = 22TypeError: 'tuple' object does not support item assignment

【錯誤分析】元祖不可變，所以不可以更改;可以用切片或合并的方式達到目的.

>>> T = (1,2,3,4)>>> (22,) + T[1:](22, 2, 3, 4)

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