python regular expression to split string and get

I'm trying to split string using regular expression with python and get all the matched literals.

RE: \w+(\.?\w+)*

this need to capture [a-zA-Z0-9_] like stuff only.

Here is example

but when I try to match and get all the contents from string, it doesn't return proper results.

Code snippet:

>>> import re
>>> from pprint import pprint
>>> pattern = r"\w+(\.?\w+)*"
>>> string = """this is some test string and there are some digits as well that need to be captured as well like 1234567890 and 321 etc. But it should also select _ as well. I'm pretty sure that that RE does exactly the same.
... Oh wait, it also need to filter out the symbols like !@#$%^&*()-+=[]{}.,;:'"`| \(`.`)/
... 
... I guess that's it."""
>>> pprint(re.findall(r"\w+(.?\w+)*", string))
[' etc', ' well', ' same', ' wait', ' like', ' it']

it's only returning some of words, but actually it should return all the words, numbers and underscore(s)[as in linked example].

python version: Python 3.6.2 (default, Jul 17 2017, 16:44:45)

Thanks.

You need to use a non-capturing group (see here why) and escape the dot (see here what chars should be escaped in regex):

>>> import re
>>> from pprint import pprint
>>> pattern = r"\w+(?:\.?\w+)*"
>>> string = """this is some test string and there are some digits as well that need to be captured as well like 1234567890 and 321 etc. But it should also select _ as well. I'm pretty sure that that RE does exactly the same.
... Oh wait, it also need to filter out the symbols like !@#$%^&*()-+=[]{}.,;:'"`| \(`.`)/
... 
... I guess that's it."""
>>> pprint(re.findall(pattern, string, re.A))
['this', 'is', 'some', 'test', 'string', 'and', 'there', 'are', 'some', 'digits', 'as', 'well', 'that', 'need', 'to', 'be', 'captured', 'as', 'well', 'like', '1234567890', 'and', '321', 'etc', 'But', 'it', 'should', 'also', 'select', '_', 'as', 'well', 'I', 'm', 'pretty', 'sure', 'that', 'that', 'RE', 'does', 'exactly', 'the', 'same', 'Oh', 'wait', 'it', 'also', 'need', 'to', 'filter', 'out', 'the', 'symbols', 'like', 'I', 'guess', 'that', 's', 'it']

Also, to only match ASCII letters, digits and _ you must pass re.A flag.

See the Python demo.