列表 += 元组与列表 = 列表 + 元组
问题描述
假设我有这些任务:
points = []
point = (1, 2)
我怎么会这样做:
points += point
它工作得很好，并且给了我点 = [1, 2].但是，如果我这样做:
It works completely fine, and gives me points = [1, 2]. However, If I do something like:
points = points + point
它给了我一个 TypeError: can only concatenate list (not "tuple") to list.不过，这些陈述不是一回事吗?
It gives me a TypeError: can only concatenate list (not "tuple") to list. Aren't these statements the same thing, though?
解决方案
不同的是，list +=等价于list.extend()，取任何可迭代并扩展列表，它作为元组工作是可迭代的.(并就地扩展列表).
The difference, is that list += is equivalent to list.extend(), which takes any iterable and extends the list, it works as a tuple is an iterable. (And extends the list in-place).
另一方面，第二个将一个新列表分配给 points，并尝试将一个列表连接到一个元组，但由于不清楚预期结果是什么(列表或元组?).
On the other hand, the second assigns a new list to points, and attempts to concatenate a list to a tuple, which isn't done as it's unclear what the expected results is (list or tuple?).
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