Python: getting substring starting and ending between two given substrings

Question

What would be the textbook way of accomplishing the following tasks:

I have a string s of the from s_s * s_l * s_q * s_r * s_e, where by * I mean the concatenation operator.

Given s, s_l and s_r I am interested in returning s_q, we may assume that s_l and s_r only occur once in s.

As an example: s = "abcdefghij", s_l = "cd", s_r = "hi" so s_q = "efg".

Would a regex approach be appropriate in this situation?

zhangxaochen · Accepted Answer · 2014-02-20 17:49:20Z

1

In [110]: s[s.find(s_l)+len(s_l): s.find(s_r)]
Out[110]: 'efg'

answered Feb 20, 2014 at 17:49

zhangxaochen

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2 Comments

bnjmn Over a year ago

You might want to use rfind on s_r to take the first occurrence from the right

zhangxaochen Over a year ago

@bnjmn the OP assumes s_r occurs only once in s ;)

ASGM · Accepted Answer · 2014-02-20 17:57:36Z

0

You could split the string, since you know that s_l and s_r only occur once each:

s = "abcdefghij"
s_l = "cd"
s_r = "hi"

print s.split(s_l)[1].split(s_r)[0] # Returns efg

You don't need to use regular expressions, because s_l and s_r are static. If you didn't know what s_l and s_r are going to be in advance, only that they match some pattern, then regular expressions might be helpful.

edited Feb 20, 2014 at 17:57

answered Feb 20, 2014 at 17:51

ASGM

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