Is there something specific for using re.search() to match multiline pattern within a function? Python

Question

I'm trying to search r'CONTENTS\.\n+CHAPTER I\.' within a string from Gutenberg project, but I'm getting AttributeError, as it doesn't match, but the same pattern does match outside the function. My code is below:

def gutenberg(url):
    responce=request.urlopen(url)
    raw=responce.read().decode('utf8')
    print(re.search(r"CONTENTS\.\n+CHAPTER I\.",raw).group())

a=gutenberg("https://www.gutenberg.org/files/76/76-0.txt")

Output:

...
print(re.search(r"CONTENTS\.\n+CHAPTER I\.",raw).group())
AttributeError: 'NoneType' object has no attribute 'group'

And outside the function:

a="""Complete









 CONTENTS.



 CHAPTER I. Civilizing"""

re.search(r"CONTENTS\.\n+CHAPTER I\.",a).group()

Output:

'CONTENTS.\n\nCHAPTER I.'

Though, it works fine within the function when there's no new line character in the pattern: print(re.search(r"CONTENTS\.",raw).group()). So, I believe I need something like flags.

What I've tried:

print(re.search(r"CONTENTS\.\n+CHAPTER I\.",raw,re.M).group())

  pattern=re.compile(r'CONTENTS.\n+CHAPTER I.')
  print(pattern.search(raw).group())

I even tried to add a backslash into my pattern: r"CONTENTS\.\\n+CHAPTER I\." - the same AttributeError.

I read about flags=regex.VERSION1 here but I couldn't find information about it in the last Python's regex guide, so I haven't tried to use it.

Any ideas how to search for multiline pattern within a function?

In general, what's confusing me much is different behavior of re.search() inside and outside the function. Is there a conception I'm not aware of?

Thanks in advance! I'll appreciate any help!

score 0 · Answer 1 · answered May 31 '22 at 03:49

No, there isn't something special, and it doesn't matter whether you're "in a function" or not. The data you pulled down from that URL simply doesn't match your pattern: it has \r\n line endings and not \n. Your "outside the function" test case with the literal string is testing on different data which does match the pattern.

Is there something specific for using re.search() to match multiline pattern within a function? Python

1 Answers1