问题
I'm trying to parse a string with multiple lines.
Suppose it is:
text = '''
Section1
stuff belonging to section1
stuff belonging to section1
stuff belonging to section1
Section2
stuff belonging to section2
stuff belonging to section2
stuff belonging to section2
'''
I want to use the finditer method of the re module to get a dictionary like:
{'section': 'Section1', 'section_data': 'stuff belonging to section1\nstuff belonging to section1\nstuff belonging to section1\n'}
{'section': 'Section2', 'section_data': 'stuff belonging to section2\nstuff belonging to section2\nstuff belonging to section2\n'}
I tried the following:
import re
re_sections=re.compile(r"(?P<section>Section\d)\s*(?P<section_data>.+)", re.DOTALL)
sections_it = re_sections.finditer(text)
for m in sections_it:
print m.groupdict()
But this results in:
{'section': 'Section1', 'section_data': 'stuff belonging to section1\nstuff belonging to section1\nstuff belonging to section1\nSection2\nstuff belonging to section2\nstuff belonging to section2\nstuff belonging to section2\n'}
So the section_data also matches Section2.
I also tried to tell the second group to match all but the first one. But this leads to no output at all.
re_sections=re.compile(r"(?P<section>Section\d)\s+(?P<section_data>^(?P=section))", re.DOTALL)
I know I could use the following re, but I'm looking for a version, where I do not have to tell what the second group looks like.
re_sections=re.compile(r"(?P<section>Section\d)\s+(?P<section_data>[a-z12\s]+)", re.DOTALL)
Thank you very much!
回答1:
Use a look-ahead to match everything up to the next section header, or the end of the string:
re_sections=re.compile(r"(?P<section>Section\d)\s*(?P<section_data>.+?)(?=(?:Section\d|$))", re.DOTALL)
Note that this needs a non-greedy .+?
as well, otherwise it'll still match all the way to the end first.
Demo:
>>> re_sections=re.compile(r"(?P<section>Section\d)\s*(?P<section_data>.+?)(?=(?:Section\d|$))", re.DOTALL)
>>> for m in re_sections.finditer(text): print m.groupdict()
...
{'section': 'Section1', 'section_data': 'stuff belonging to section1\nstuff belonging to section1\nstuff belonging to section1\n'}
{'section': 'Section2', 'section_data': 'stuff belonging to section2\nstuff belonging to section2\nstuff belonging to section2'}
来源:https://stackoverflow.com/questions/15953406/python-regular-expression-matching-multiple-lines-re-dotall