How to Extract Substrings Between Markers in Python Using Regular Expressions?

Substrands Extraction between Markers

Given a string and a pair of markers, the task is to extract the substring between these markers. For instance, consider the string 'gfgfdAAA1234ZZZuijjk'. The objective is to obtain the '1234' portion.

In Python, regular expressions provide a powerful solution for this problem. Consider the following code snippet:

import re

text = 'gfgfdAAA1234ZZZuijjk'

m = re.search('AAA(.+?)ZZZ', text)
if m:
    found = m.group(1)

# found: 1234

The expression 'AAA(. ?)ZZZ' matches any substring between 'AAA' and 'ZZZ'. The parentheses in the expression capture the substring as a group, and the '. ?' quantifier ensures that it matches any number of characters non-greedily.

The re.search() function finds the first occurrence of the pattern in the text and returns a match object, which contains the captured group(s). The group(1) method extracts the substring between the markers and assigns it to the found variable.

Alternatively, the try-except block can handle potential errors:

import re

text = 'gfgfdAAA1234ZZZuijjk'

try:
    found = re.search('AAA(.+?)ZZZ', text).group(1)
except AttributeError:
    # AAA, ZZZ not found in the original string
    found = '' # Your error handling here

# found: 1234

This approach guarantees that the program will continue running even if the markers are not present in the text, as it handles the AttributeError that occurs when the group(1) method fails.

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