关于 list.extend(tuple) [英] About list.extend(tuple)

问题描述

代码在这里:

<预><代码>>>>a = ['xyz']>>>b = (5,)>>>a.扩展(b)>>>一种['xyz', 5]

我查了很多资料，但他们都告诉我:

list.extend(seq)seq -- 这是元素列表

我想知道为什么列表可以扩展元组.
谢谢.

解决方案

如果查看 docstring for extend ，您会发现它可以通过任何方式扩展可迭代:

""" L.extend(iterable) -> None -- 通过附加来自可迭代对象 """ 的元素来扩展列表

这意味着您不仅限于lists 或tuples，还包括strings、set>s 和其他可迭代对象:

 for iterable in ('ab', set([1, 2, 3]), {1:2, 3:4}, (0, 1)):l = [1]l.extend(可迭代)打印(升)

打印:

[1, 'a', 'b'][1, 1, 2, 3][1, 1, 3] # Note 字典默认遍历键[1, 0, 1]

the code is here:

>>> a = ['xyz']
>>> b = (5,)
>>> a.extend(b)
>>> a
['xyz', 5]

I checked a lot of information,but they both told me that:

list.extend(seq)
seq -- This is the list of elements

I want know why list can extend a tuple.
thx.

解决方案

If you look at the docstring for extend, you will see that it can be extended by any iterable:

""" L.extend(iterable) -> None -- extend list by appending elements from the iterable """

This means you are not only limited to lists or tuples, but also strings, sets, and other iterables:

for iterable in ('ab', set([1, 2, 3]), {1:2, 3:4}, (0, 1)):
    l = [1]
    l.extend(iterable)
    print(l)

This prints:

[1, 'a', 'b']
[1, 1, 2, 3]
[1, 1, 3] # Note dictionaries iterate over keys by default
[1, 0, 1]

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