问题描述
我需要明白为什么:
years = range(2010,2016)
years.append(0)
是可能的，返回:
[2010,2011,2012,2013,2014,2015,0]
和
years = range(2010,2016).append(0)
或
years = [0].extend(range(2010,2016))
不工作?
我知道这是我收到的消息中的类型错误.但我想在这背后有更多的解释.
I understand that it is a type error from the message I got. But I'd like to have a bit more explanations behind that.
推荐答案
你正在存储 list.append() 或 list.extend() 方法的结果;两者都更改列表就地并返回None.他们确实不会再次返回列表对象.
You are storing the result of the list.append() or list.extend() method; both alter the list in place and return None. They do not return the list object again.
不存储 None 结果；存储 range() 结果，then 扩展或追加.或者，使用串联:
Do not store the None result; store the range() result, then extend or append. Alternatively, use concatenation:
years = range(2010, 2016) + [0]
years = [0] + range(2010, 2016)
请注意，我假设您使用的是 Python 2(否则您的第一个示例将无法正常工作).在 Python 3 中 range() 不会产生列表；您必须使用 list() 函数将其转换为一个:
Note that I'm assuming you are using Python 2 (your first example would not work otherwise). In Python 3 range() doesn't produce a list; you'd have to use the list() function to convert it to one:
years = list(range(2010, 2016)) + [0]
years = [0] + list(range(2010, 2016))
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