如果我有清单：
lista=[99, True, "Una Lista", [1,3]]
下面的表达是什么意思？
mi_var = lista[0:4:2]
语法lista[0:4:2]被称为扩展了slice语法，并返回列表的一个slice，该列表由索引0（包括索引0）到4（不包括索引4）的元素组成，但仅包括偶数索引（步骤=2）。
在您的示例中，它将给出[99，“Una Lista”]。更一般地说，您可以通过编写lista[：：2]来获得由偶数索引处的每个元素组成的切片。这与列表的长度无关，因为起始参数和结束参数分别默认为0和列表的长度。
切片的一个有趣的功能是，您还可以指定给它们以修改原始列表，或者删除切片以从原始列表中删除元素。
>>> x = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> x[::2] = [ a , b , c , d , e ] # Assign to index 0, 2, 4, 6, 8
>>> x
[ a , 1, b , 3, c , 5, d , 7, e , 9]
>>> del x[:5] # Remove the first 5 elements
>>> x
[5, d , 7, e , 9]
在列表中从0到3（因为排除了4，[start，end））遍历两个元素。结果如预期的那样是[99，Una Lista]，并存储在列表中，mi_var
一种只是跑步和观看的方式：
>>> lista=[99, True, "Una Lista", [1,3]]
>>> lista[0:4:2]
[99, Una Lista ]
这是一个切片表示法，它创建了一个新的列表，该列表由lista的每一个元素组成，从索引0开始，直到但不包括索引4
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