Match text between two strings with regular expression

Question

I would like to use a regular expression that matches any text between two strings:

Part 1. Part 2. Part 3 then more text

In this example, I would like to search for “Part 1” and “Part 3” and then get everything in between which would be: “. Part 2. “

I’m using Python 2x.

Asked By: Carlos Muñiz

||

Source

Answer 1

Use re.search

>>> import re
>>> s = 'Part 1. Part 2. Part 3 then more text'
>>> re.search(r'Part 1.(.*?)Part 3', s).group(1)
' Part 2. '
>>> re.search(r'Part 1(.*?)Part 3', s).group(1)
'. Part 2. '

Or use re.findall, if there are more than one occurances.

Answered By: Avinash Raj

Answer 2

With regular expression:

>>> import re
>>> s = 'Part 1. Part 2. Part 3 then more text'
>>> re.search(r'Part 1(.*?)Part 3', s).group(1)
'. Part 2. '

Without regular expression, this one works for your example:

>>> s = 'Part 1. Part 2. Part 3 then more text'
>>> a, b = s.find('Part 1'), s.find('Part 3')
>>> s[a+6:b]
'. Part 2. '

Answered By: lord63. j

Answer 3

I feel these example with increasing complexity are interesting:

ppt = 'abc HERE abc'
ept = 'abc TERM abc'
re_ppt = ppt.replace('HERE', '(.+)')
print()
print(f'{re_ppt=}')
out = re.search(pattern=re_ppt, string=ept)
print(out)
print(out.groups())

ppt = 'abc HERE abc HERE abc'
ept = 'abc TERM1 abc TERM2 abc'
re_ppt = ppt.replace('HERE', '(.+)')
print()
print(f'{re_ppt=}')
out = re.search(pattern=re_ppt, string=ept)
print(out)
print(out.groups())

print()
ppt = """(fun n : nat =>
 nat_ind (fun n0 : nat => n0 + 0 = n0) ?Goal"""
print(f"{ppt=}")
ept = """(fun n : nat =>
 nat_ind (fun n0 : nat => n0 + 0 = n0) (eq_refl : 0 + 0 = 0)"""
print(f'{ept=}')
pattern_meta_var = r'?(w)+'
_ppt = re.sub(pattern=pattern_meta_var, repl='HERE', string=ppt)
print(f'{ppt=}')
_ppt = re.escape(_ppt)
print(f'{ppt=}')
re_ppt = _ppt.replace('HERE', '(.+)')
print(f'{re_ppt=}')
out = re.search(pattern=re_ppt, string=ept)
print(out)
print(out.groups())

print()

# sometimes the actual proof term missing won't have white spaces surrounding it but the ppt will have surrounding spaces where the hole
# would be. So in goal cames I removed the surrounding whitespaces. Then inserted a regex that accepts a hole with or
# without surrounding white spaces. That way in case the proof term in the hole does have surrounding white spaces then
# the regex hole catcher would match it anyway.
ppt = """n   (fun (n' : nat) (IH : n' + 0 = n') => ?Goal0) n)"""
ept = """n   (fun (n' : nat) (IH : n' + 0 = n') =>nteq_ind_r (fun n0 : nat => S n0 = S n') eq_refl IH : S n' + 0 = S n') n)"""
print(f"{ppt=}")
print(f'{ept=}')
pattern_meta_var = r's*?(w)+s*'
_ppt = re.sub(pattern=pattern_meta_var, repl='HERE', string=ppt)
print(f'{_ppt=}')
_ppt = re.escape(_ppt)
print(f'{_ppt=}')
re_ppt = _ppt.replace('HERE', 's*(.+)s*')
print(f'{re_ppt=}')
out = re.search(pattern=re_ppt, string=ept)
print(out)
assert out is not None, f'expected two holes matched but go {out=}'
print(out.groups())

print()
ppt = """(fun n : nat =>
 nat_ind (fun n0 : nat => n0 + 0 = n0) ?Goal
   (fun (n' : nat) (IH : n' + 0 = n') => ?Goal0) n)"""
print(f"{ppt=}")
ept = """(fun n : nat =>
 nat_ind (fun n0 : nat => n0 + 0 = n0) (eq_refl : 0 + 0 = 0)
   (fun (n' : nat) (IH : n' + 0 = n') =>
    eq_ind_r (fun n0 : nat => S n0 = S n') eq_refl IH : S n' + 0 = S n') n)"""
print(f'{ept=}')
pattern_meta_var = r's*?(w)+s*'
_ppt = re.sub(pattern=pattern_meta_var, repl='HERE', string=ppt)
print(f'{_ppt=}')
_ppt = re.escape(_ppt)
print(f'{_ppt=}')
re_ppt = _ppt.replace('HERE', 's*(.+)s*')
print(f'{re_ppt=}')
out = re.search(pattern=re_ppt, string=ept)
print(out)
print(out.groups())

Answered By: Charlie Parker

Match text between two strings with regular expression

Question:

Answers: