IPython的有序列拆封

Question

怪異的行爲我有一個奇怪的行爲與序列中的IPython

In [12]: items = [1, 10, 7, 4, 5, 9] 

In [13]: head, *tail = items 
    File "<ipython-input-13-34256df22cca>", line 1 
    head, *tail = items 
     ^
SyntaxError: invalid syntax 

Answer 1

這句法（PEP 3132 - Extended Iterable Unpacking）是在Python 3.0中引入拆包。檢查你的python版本。

在Python 3.3：

>>> items = [1, 10, 7, 4, 5, 9] 
>>> head, *tail = items 
>>> head 
1 
>>> tail 
[10, 7, 4, 5, 9] 

在Python 2.7，它提出了語法錯誤：

>>> items = [1, 10, 7, 4, 5, 9] 
>>> head, *tail = items 
    File "<stdin>", line 1 
    head, *tail = items 
     ^
SyntaxError: invalid syntax 
>>> head, tail = items[0], items[1:] # workaround 
>>> head 
1 
>>> tail 
[10, 7, 4, 5, 9]