ErrorCode：UnboundLocalError on line 10

下面的python代碼的第10行有一個UnboundLocalError。任何人都可以請教我如何解決這個問題？ErrorCode：UnboundLocalError on line 10

def answer(data, n): 
    new_data = [] 
    for each_integer in data: 
     new_data = [each_integer for each_integer in data if data.count(each_integer) == n] 
    if n > 1: 
     new_data = data 
    print("\n\nNew Data") 
    print(new_data) 

supplied_data = [53, 85, 29, 23, 29, 26, 88, 78, 5, 75, 74, 44, 33, 62, 98, 50, 89, 93, 24, 14, 74, 49, 83, 45, 41, 14, 68, 76, 68, 8, 77, 85, 17, 3, 9, 30, 71, 48, 18, 25, 86, 55, 55, 20, 74, 76, 99, 87, 59, 87, 36, 29, 29, 8, 22, 65, 1, 18, 23, 5, 13, 60, 7, 5, 98, 61, 78, 64, 36, 60, 49, 57, 31, 32, 41, 86, 52, 90, 9, 55, 35, 35, 2, 44, 8, 19, 96, 81, 68, 7, 8, 51, 9, 76, 12, 96, 61, 99, 74]  
answer(supplied_data, 0) 
answer(supplied_data, 1) 
answer(supplied_data, 6)

回溯

 
    >>> def answer(data, n): 
    ...  for each_integer in data: 
    ...   new_data = [each_integer for each_integer in data if data.count(each_integer) == n] 
    ...  if n > 1: 
    ...   new_data = data 
    ...  print("\n\nNew Data") 
    ...  print(new_data) 
    ... 
    ... supplied_data = [53, 85, 29, 23, 29, 26, 88, 78, 5, 75, 74, 44, 33, 62, 98, 50, 89, 93, 24, 14, 74, 49, 83, 45, 41, 14, 68, 76, 68, 8, 77, 85, 17, 3, 9, 30, 71, 48, 18, 25, 86, 55, 55, 20, 
    74, 76, 99, 87, 59, 87, 36, 29, 29, 8, 22, 65, 1, 18, 23, 5, 13, 60, 7, 5, 98, 61, 78, 64, 36, 60, 49, 57, 31, 32, 41, 86, 52, 90, 9, 55, 35, 35, 2, 44, 8, 19, 96, 81, 68, 7, 8, 51, 9, 76, 12 
    , 96, 61, 99, 74] 
     File "", line 9 
     supplied_data = [53, 85, 29, 23, 29, 26, 88, 78, 5, 75, 74, 44, 33, 62, 98, 50, 89, 93, 24, 14, 74, 49, 83, 45, 41, 14, 68, 76, 68, 8, 77, 85, 17, 3, 9, 30, 71, 48, 18, 25, 86, 55, 55, 20, 
    74, 76, 99, 87, 59, 87, 36, 29, 29, 8, 22, 65, 1, 18, 23, 5, 13, 60, 7, 5, 98, 61, 78, 64, 36, 60, 49, 57, 31, 32, 41, 86, 52, 90, 9, 55, 35, 35, 2, 44, 8, 19, 96, 81, 68, 7, 8, 51, 9, 76, 12 
    , 96, 61, 99, 74] 
        ^
    SyntaxError: invalid syntax 
    >>> answer(supplied_data, 0) 
    Traceback (most recent call last): 
     File "", line 1, in 
    NameError: name 'answer' is not defined 
    >>> answer(supplied_data, 1) 
    Traceback (most recent call last): 
     File "", line 1, in 
    NameError: name 'answer' is not defined 
    >>> answer(supplied_data, 6) 
    Traceback (most recent call last): 
     File "", line 1, in 
    NameError: name 'answer' is not defined 
    >>>

來源

2017-01-16 Caspian

此代碼不會給出該錯誤。如果你遇到錯誤，你應該發佈完整的回溯。（我最初表示它「工作正常」，但當然不會; for循環和if語句都毫無意義）。 –

始終發佈**完整回溯**。 –

@DanielRoseman如果'data'爲空且'n <= 1'，那麼它將會生效 –

的問題是你有一個分支機構在使用new_data你的邏輯，但它是可能的new_data從未定義。當data爲空會出現這種情況，所以你永遠不會進入for循環體，創造new_data和n <= 1，即你進入else-block，在那裏你使用new_data沒有它被定義。

請參見：

>>> answer([],1) 


New Data 
Traceback (most recent call last): 
    File "<stdin>", line 1, in <module> 
    File "<stdin>", line 10, in answer 
UnboundLocalError: local variable 'new_data' referenced before assignment

你可以通過把new_data = data在你的函數的頂部迅速解決這個問題。老實說，這種方法效率很低，因爲它在二次時間內工作。 some_list.count每次迭代整個列表！所以，最好使一次通過計數元素，然後再通過一次過濾 - 這將是線性時間：

>>> from collections import Counter 
>>> def answer(data, n): 
... counts = Counter(data) 
... return [e for e in data if counts[e] == n] 
... 
>>> answer(data, 6) 
[] 
>>> answer(data, 2) 
[85, 23, 78, 44, 98, 14, 49, 41, 14, 85, 18, 86, 99, 87, 87, 36, 18, 23, 60, 7, 98, 61, 78, 36, 60, 49, 41, 86, 35, 35, 44, 96, 7, 96, 61, 99] 
>>> answer(data, 3) 
[5, 68, 76, 68, 9, 55, 55, 76, 5, 5, 9, 55, 68, 9, 76] 
>>> answer(data, 4) 
[29, 29, 74, 74, 8, 74, 29, 29, 8, 8, 8, 74] 
>>> answer(data, 5)

來源

2017-01-16 18:41:46

ErrorCode：UnboundLocalError on line 10

回答

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