从函数返回单个项目的元组 [英] Returning tuple with a single item from a function

问题描述

刚刚在Python中遇到了这种奇怪的东西，并且认为我会将它记录下来 在这里写下它是一个问题，以防其他人试图找到一个同样没有结果的答案搜索条件我是

看起来像tuple unpacking使得它不能返回长度为1的元组，如果您期望迭代返回值。虽然看起来似乎在欺骗。请参阅答案。

 >>> def returns_list_of_one（a）：
 ... return [a] 
 ... 
>>> def returns_tuple_of_one（a）：
 ... return（a）
 ... 
>>> def returns_tuple_of_two（a）：
 ... return（a，a）
 ... 
>>> for n in returns_list_of_one（10）：
 ... print n 
 ... 
 10 
>>> for n in returns_tuple_of_two（10）：
 ... print n 
 ... 
 10 
 10 
>>> for n in returns_tuple_of_one（10）：
 ... print n 
 ... 
 Traceback（最近的最后一次调用）：
文件< stdin>，第1行，在< module> 
 TypeError：'int'对象不可迭代
>>> 
  

解决方案

您需要明确地将其设置为一个元组教程）：

  def returns_tuple_of_one（a）：
 return（a，）
  

Just came across this little bit of weirdness in Python and thought I'd document it write it as a question here in case anyone else is trying to find an answer with the same fruitless search terms I was

Looks like tuple unpacking makes it so you can't return a tuple of length 1 if you're expecting to iterate over the return value. Although it seems that looks are deceiving. See the answers.

>>> def returns_list_of_one(a):
...     return [a]
...
>>> def returns_tuple_of_one(a):
...     return (a)
...
>>> def returns_tuple_of_two(a):
...     return (a, a)
...
>>> for n in returns_list_of_one(10):
...    print n
...
10
>>> for n in returns_tuple_of_two(10):
...     print n
...
10
10
>>> for n in returns_tuple_of_one(10):
...     print n
...
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'int' object is not iterable
>>>

解决方案

You need to explicitly make it a tuple (see the official tutorial):

def returns_tuple_of_one(a):
    return (a, )

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