Python 列表索引中的冒号 (:)
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Colon (:) in Python list index
提问by kuriouscoder
I'm new to Python. I see :used in list indices especially when it's associated with function calls.
我是 Python 的新手。我看到:在列表索引中使用，特别是当它与函数调用相关联时。
Python 2.7 documentation suggests that lists.appendtranslates to a[len(a):] = [x]. Why does one need to suffix len(a)with a colon?
Python 2.7 文档建议lists.append转换为a[len(a):] = [x]. 为什么需要以len(a)冒号作为后缀？
I understand that :is used to identify keys in dictionary.
我知道它:用于识别字典中的键。
采纳答案by soulseekah
:is the delimiter of the slice syntax to 'slice out' sub-parts in sequences , [start:end]
:是切片语法的分隔符，用于“切出”序列中的子部分， [start:end]
[1:5] is equivalent to "from 1 to 5" (5 not included)
[1:] is equivalent to "1 to end"
[len(a):] is equivalent to "from length of a to end"
Watch https://youtu.be/tKTZoB2Vjuk?t=41m40sat around 40:00 he starts explaining that.
在 40:00 左右观看https://youtu.be/tKTZoB2Vjuk?t=41m40s，他开始解释。
Works with tuples and strings, too.
也适用于元组和字符串。
回答by joni
slicing operator. http://docs.python.org/tutorial/introduction.html#stringsand scroll down a bit
切片运算符。http://docs.python.org/tutorial/introduction.html#strings并向下滚动一点
回答by GISman
a[len(a):]- This gets you the length of a to the end. It selects a range. If you reverse a[:len(a)]it will get you the beginning to whatever is len(a).
a[len(a):]- 这会让你得到 a 到最后的长度。它选择一个范围。如果你扭转 a[:len(a)]它会让你开始到任何事情len(a)。
