RegEx Tokenizer: split text into words, digits, punctuation, and spacing (do not delete anything)

Question

I almost found the answer to this question in this thread (samplebias's answer); however I need to split a phrase into words, digits, punctuation marks, and spaces/tabs. I also need this to preserve the order in which each of these things occurs (which the code in that thread already does).

So, what I've found is something like this:

    from nltk.tokenize import *
    txt = "Today it's   07.May 2011. Or 2.999."
    regexp_tokenize(txt, pattern=r'\w+([.,]\w+)*|\S+')
    ['Today', 'it', "'s", '07.May', '2011', '.', 'Or', '2.999', '.']

But this is the kind of list I need to yield:

    ['Today', ' ', 'it', "'s", ' ', '\t', '07.May', ' ', '2011', '.', ' ', 'Or', ' ', '2.999', '.']

Regex has always been one of my weakpoints so after a couple hours of research I'm still stumped. Thank you!!

Answer 1

I think that something like this should work for you. There is probably more in that regex than there needs to be, but your requirements are somewhat vague and don't exactly match up with the expected output you provided.

>>> txt = "Today it's \t07.May 2011. Or 2.999."
>>> p = re.compile(r"\d+|[-'a-z]+|[ ]+|\s+|[.,]+|\S+", re.I)
>>> slice_starts = [m.start() for m in p.finditer(txt)] + [None]
>>> [txt[s:e] for s, e in zip(slice_starts, slice_starts[1:])]
['Today', ' ', "it's", ' ', '\t', '07', '.', 'May', ' ', '2011', '.', ' ', 'Or', ' ', '2', '.', '999', '.']