python - Regex to find all sentences of text?

Question

I have been trying to teach myself Regexes in python and I decided to print out all the sentences of a text. I have been tinkering with the regular expressions for the past 3 hours to no avail.

I just tried the following but couldn't do anything.

p = open('anan.txt')
process = p.read()
regexMatch = re.findall('^[A-Z].+s+[.!?]$',process,re.I)
print regexMatch
p.close()

My input file is like this:

OMG is this a question ! Is this a sentence ? My.
name is.

This prints no outputs. But when I remove "My. name is.", it prints OMG is this a question and Is this a sentence together as if it only reads the first line.

What is the best solution of regex that can find all sentences in a text file - regardless if the sentence carries to new line or so - and also reads the entire text? Thanks.

Answer 1

Something like this works:

## pattern: Upercase, then anything that is not in (.!?), then one of them
>>> pat = re.compile(r'([A-Z][^.!?]*[.!?])', re.M)
>>> pat.findall('OMG is this a question ! Is this a sentence ? My. name is.')
['OMG is this a question !', 'Is this a sentence ?', 'My.']

Notice how name is. is not in the result because it does not start with a uppercase letter.

Your problem comes from the use of the ^$ anchors, they work on the whole text.