Python Untokenize a sentence

Question

There are so many guides on how to tokenize a sentence, but i didn\'t find any on how to do the opposite.

 import nltk
 words = nltk.word_tokenize(\"I\'ve found          


        

Answer 1

I propose to keep offsets in tokenization: (token, offset). I think, this information is useful for processing over the original sentence.

import re
from nltk.tokenize import word_tokenize

def offset_tokenize(text):
    tail = text
    accum = 0
    tokens = self.tokenize(text)
    info_tokens = []
    for tok in tokens:
        scaped_tok = re.escape(tok)
        m = re.search(scaped_tok, tail)
        start, end = m.span()
        # global offsets
        gs = accum + start
        ge = accum + end
        accum += end
        # keep searching in the rest
        tail = tail[end:]
        info_tokens.append((tok, (gs, ge)))
    return info_token

sent = '''I've found a medicine for my disease.

This is line:3.'''

toks_offsets = offset_tokenize(sent)

for t in toks_offsets:
(tok, offset) = t
print (tok == sent[offset[0]:offset[1]]), tok, sent[offset[0]:offset[1]]

Gives:

True I I
True 've 've
True found found
True a a
True medicine medicine
True for for
True my my
True disease disease
True . .
True This This
True is is
True line:3 line:3
True . .