Extracting String within strings using Regex Python

Question

Say i have this string

"Input:Can we book an hotel in Lagos ? Parse: book VB ROOT +-- Can MD aux +-- we PRP nsubj +-- hotel NN dobj | +-- an DT det | +-- in IN prep | +-- Lagos NNP pobj +-- ? . punct "

and i want to get a list like this

['book VB ROOT', 'Can MD aux',..., '? . punct']

using regular expression.

I have tried doing

result = re.findall('\||\+-- (.*?)\+--|\| ', result, re.DOTALL)

any help would be appreciated

Do you really have to use regex? You can achieve what you want with a simple split() — Farhan.K
– Farhan.K, Commented Jun 3, 2016 at 12:40

Kasravnd · Accepted Answer · 2016-06-03 12:47:37Z

1

Without regex by playing with built-in functions and methods:

>>> filter(bool, map(str.strip, s.replace('+--', '|').split('Parse:')[1].split('|')))
['book VB ROOT', 'Can MD aux', 'we PRP nsubj', 'hotel NN dobj', 'an DT det', 'in IN prep', 'Lagos NNP pobj', '? . punct']

answered Jun 3, 2016 at 12:47

Kasravnd

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Avinash Raj · Accepted Answer · 2016-06-03 13:16:17Z

0

I would use re.split..

>>> s = 'Can we book an hotel in Lagos ? Parse: book VB ROOT  +-- Can MD aux  +-- we PRP nsubj  +-- hotel NN dobj  |   +-- an DT det  |   +-- in IN prep  |       +-- Lagos NNP pobj  +-- ? . punct'
>>> re.split(r'\s*\|?\s*\+\s*--\s*', s.split('Parse:')[1].strip())
['book VB ROOT', 'Can MD aux', 'we PRP nsubj', 'hotel NN dobj', 'an DT det', 'in IN prep', 'Lagos NNP pobj', '? . punct']

edited Jun 3, 2016 at 13:16

answered Jun 3, 2016 at 12:42

Avinash Raj

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1 Comment

Jonathan Itakpe Over a year ago

not working this is the output ['Can we book an hotel in Lagos ? Parse'] note the string is "Input: Can we book an hotel in Lagos ? Parse: book VB ROOT +-- Can MD aux +-- we PRP nsubj +-- hotel NN dobj | +-- an DT det | +-- in IN prep | +-- Lagos NNP pobj +-- ? . punct"

jaap3 · Accepted Answer · 2016-06-03 18:12:02Z

0

Here's a version that does use a regex, but doesn't require looping over all the parts twice:

def extract(line):
    _, _, parts = line.strip().partition(' Parse: ')
   return re.split('(?: \|)? \+-- ', parts)

line = "Input:Can we book an hotel in Lagos ? Parse: book VB ROOT +-- Can MD aux +-- we PRP nsubj +-- hotel NN dobj | +-- an DT det | +-- in IN prep | +-- Lagos NNP pobj +-- ? . punct "
print(extract(line))
>>> ['book VB ROOT', 'Can MD aux', 'we PRP nsubj', 'hotel NN dobj', 'an DT det', 'in IN prep', 'Lagos NNP pobj', '? . punct']

answered Jun 3, 2016 at 18:12

jaap3

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