本文介绍了如何找到项目在列表中出现的第n次索引?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
鉴于:
x = ['w','e','s','s','s ','z','z','s']每次出现 s 出现在以下指数中:
第一名:2 第二名:3名 3rd:4 4th:7
如果我做 x.index('s')我将获得第一个索引。
如何获得第4个 s的索引?<使用列表理解和 枚举 :
>>> x = ['w','e','s','s','s','z','z','s'] >>> [i for i,n in enumerate(x)if n =='s'] [0] 2 >>> [i for i,n in enumerate(x)if n =='s'] [1] 3 >>> [i for i,n in enumerate(x)if n =='s'] [2] 4 >>> [i for i,n in enumerate(x)if n =='s'] [3] 7
Given:
x = ['w', 'e', 's', 's', 's', 'z','z', 's']Each occurrence of s appears at the following indices:
1st: 2 2nd: 3 3rd: 4 4th: 7
If I do x.index('s') I will get the 1st index.
How do I get the index of the 4th s?
解决方案Using list comprehension and enumerate:
>>> x = [ 'w', 'e', 's', 's', 's', 'z','z', 's'] >>> [i for i, n in enumerate(x) if n == 's'][0] 2 >>> [i for i, n in enumerate(x) if n == 's'][1] 3 >>> [i for i, n in enumerate(x) if n == 's'][2] 4 >>> [i for i, n in enumerate(x) if n == 's'][3] 7
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如何找到项目在列表中出现的第n次索引?
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