列表+ =元组vs列表=列表+元组

问题描述

假设我有这些任务:

points = []
point = (1, 2)

怎么办?

points += point

它完全可以正常工作，并给我分= [1，2].但是，如果我做类似的事情:

points = points + point

它给了我TypeError:只能串联列表(而不是元组")到列表.这些陈述不是一回事吗?

解决方案

区别在于，list +=等效于list.extend()，它接受任何可迭代并扩展了列表，它作为元组是可迭代的. (并就地扩展列表).

另一方面，第二个方法为points分配了一个新列表，并尝试将一个列表连接到一个元组，但由于尚不清楚预期的结果是什么(列表或元组?)，所以没有这样做. /p>

Let's say I have these assignments:

points = []
point = (1, 2)

How come when I do this:

points += point

It works completely fine, and gives me points = [1, 2].However, If I do something like:

points = points + point

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

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).

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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