查找满足给定条件的列表块的开始和结束索引 [英] Find starting and ending indices of list chunks satisfying given condition

问题描述

我正在尝试在列表中查找正数块的开始和结束索引.

I am trying to find the start and stop indices of chunks of positive numbers in a list.

cross = [7,5,8,0,0,0,0,2,5,8,0,0,0,0,8,7,9,3,0,0,0,3,2,1,4,5,0,0,0,7,5] 

对于给定的示例输入，所需的输出为:

For the given example input, the desired output is:

[(0, 2), (7, 9), (14, 17), (21, 25), (29, 30)]

推荐答案

如何使用一些标志来跟踪您在检查过程中的位置以及使用一些变量来保存历史信息?

How about using some flags to track where you are in the checking process and some variables to hold historical info?

这不是超级优雅的代码，但我认为它很容易理解，并且对于您给出的用例也相当健壮.

This is not super elegant code but it is fairly simple to understand I think and fairly robust for the use case you gave.

我的代码

cross = [7,5,8,0,0,0,0,2,5,8,0,0,0,0,8,7,9,3,0,0,0,3,2,1,4,5,0,0,0,7,5] 
foundstart = False
foundend = False
startindex = 0
endindex = 0
for i in range(0, len(cross)):
    if cross[i] != 0:
        if not foundstart:
            foundstart = True
            startindex = i
    else:
        if foundstart:
            foundend = True
            endindex = i - 1

    if foundend:
        print(startindex, endindex)
        foundstart = False
        foundend = False
        startindex = 0
        endindex = 0

if foundstart:
    print(startindex, len(cross)-1)

输出

0 2
7 9
14 17
21 25
29 30

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