>>> [1,2,3,4,5][:3] # every item with an index position < 3
[1, 2, 3]
>>> [1,2,3,4,5][3:] # every item with an index position >= 3
[4, 5]
>>> [1,2,3,4,5][2:3] # every item with an index position within the interval [2,3)
[3]
>>> [1,2,3,4,5][::2] # select every second item from list
[1, 3, 5]
>>> [1,2,3,4,5][::-1] # select every single item in reverse order
[5,4,3,2,1]
>>> [1,2,3,4,5][1:4:2] # every second item from subsequence [1,4) = [2,3,4]
[2, 4]
我认为这会被认为是“Python式”的:
编辑:由于几秒钟后这个答案就变得多余,我将尝试提供一些背景信息:
数组切片允许在序列(如字符串列表)中进行快速选择。一维序列的子序列可以由左端点和右端点的索引指定:
注意左边的endpoint is included,右边的不是。您可以添加第三个参数以仅选择序列的第
n
个元素:通过将列表转换为numpy数组,甚至可以执行多维切片:
Sequence Slicing是你要找的。在这种情况下,您需要将序列分割到前三个元素以打印它们。
甚至,您也不需要在序列上循环,只需join用换行符将其打印出来
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