finding number of repetitive string occurrences

Question

My line is:

line = "aaaaaaaaaaaaaaxxxxxxxxxxxxxxbbbbbbbbbbbbxxxxxxxxxxxxxxxxxxxbbbbbbbbbbb"

How can I find number of patches of "xxxxx" in line? For example above the answer would be 2.

Note that the number of 'x's may vary.

i tried s.find('x') and s.rfind('x'), but it does not give result i want — ana, Aug 22 '17 at 12:42

score 3 · Answer 1 · answered Aug 22 '17 at 12:50

3

This is a good example of where regex can be quite useful. I'm not the world's best at regex, but here's a snippet that works:

import re

line = "aaaaaaaaaaaaaaxxxxxxxxxxxxxxbbbbbbbbbbbbxxxxxxxxxxxxxxxxxxxbbbbbbbbbbb"
patches = len(re.findall(r"(x+)", line))

This works by matching any group of 1 or more 'x' no matter how long.

answered Aug 22 '17 at 12:50

bendl

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This is another one line solution. Thanx – ana Aug 22 '17 at 13:08
how can i get starting and ending index of each such patch? – ana Aug 23 '17 at 10:16
[Here's](https://stackoverflow.com/questions/3519565/find-the-indexes-of-all-regex-matches-in-python) a question that does what you're looking for! – bendl Aug 23 '17 at 12:15

Jonas Adler · Answer 2 · 2017-08-22T12:53:54.743

1

You can use groupby to group each "patch" and then count the number of occurances:

from itertools import groupby

line = 'aaaaaaaaaaaaaaxxxxxxxxxxxxxxbbbbbbbbbbbbxxxxxxxxxxxxxxxxxxxbbbbbbbbbbb'
number_of_x = sum(ch == 'x' for ch, _ in groupby(line))

edited Aug 22 '17 at 12:53

answered Aug 22 '17 at 12:48

Jonas Adler

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that's seriously beautiful! – Ma0 Aug 22 '17 at 12:51
Thanks Jonas. It works perfectly. I wonder when would I be able to write code like this. – ana Aug 22 '17 at 12:55

finding number of repetitive string occurrences

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