Splitting on regex without removing delimiters

Question

So, I would like to split this text into sentences.

s = "You! Are you Tom? I am Danny."

so I get:

["You!", "Are you Tom?", "I am Danny."]

That is I want to split the text by the regex '[.!\?]' without removing the delimiters. What is the most pythonic way to achieve this in python?

I am aware of these questions:

JS string.split() without removing the delimiters

Python split() without removing the delimiter

But my problem has various delimiters (.?!) which complicates the problem.

Answer 1

You can use re.findall with regex .*?[.!\?]; the lazy quantifier *? makes sure each pattern matches up to the specific delimiter you want to match on:

import re

s = """You! Are you Tom? I am Danny."""
re.findall('.*?[.!\?]', s)
# ['You!', ' Are you Tom?', ' I am Danny.']

Answer 2

If Python supported split by zero-length matches, you could achieve this by matching an empty string preceded by one of the delimiters:

(?<=[.!?])

Demo: https://regex101.com/r/ZLDXr1/1

Unfortunately, Python does not support split by zero-length matches. Yet the solution may still be useful in other languages that support lookbehinds.

However, based on you input/output data samples, you rather need to split by spaces preceded by one of the delimiters. So the regex would be:

(?<=[.!?])\s+

Demo: https://regex101.com/r/ZLDXr1/2

Python demo: https://ideone.com/z6nZi5

If the spaces are optional, the re.findall solution suggested by @Psidom is the best one, I believe.