text_preprocessing.py

import re
import string
from bs4 import BeautifulSoup


contraction_mapping = {"ain't": "is not", "aren't": "are not", "can't": "cannot", "'cause": "because", "could've": "could have", "couldn't": "could not",
                       "didn't": "did not",  "doesn't": "does not", "don't": "do not", "hadn't": "had not", "hasn't": "has not", "haven't": "have not",
                       "he'd": "he would", "he'll": "he will", "he's": "he is", "how'd": "how did", "how'd'y": "how do you", "how'll": "how will",
                       "how's": "how is",  "I'd": "I would", "I'd've": "I would have", "I'll": "I will", "I'll've": "I will have", "I'm": "I am",
                       "I've": "I have", "i'd": "i would", "i'd've": "i would have", "i'll": "i will",  "i'll've": "i will have", "i'm": "i am",
                       "i've": "i have", "isn't": "is not", "it'd": "it would", "it'd've": "it would have", "it'll": "it will", "it'll've": "it will have",
                       "it's": "it is", "let's": "let us", "ma'am": "madam", "mayn't": "may not", "might've": "might have", "mightn't": "might not",
                       "mightn't've": "might not have", "must've": "must have", "mustn't": "must not", "mustn't've": "must not have", "needn't": "need not",
                       "needn't've": "need not have", "o'clock": "of the clock", "oughtn't": "ought not", "oughtn't've": "ought not have", "shan't": "shall not",
                       "sha'n't": "shall not", "shan't've": "shall not have", "she'd": "she would", "she'd've": "she would have", "she'll": "she will",
                       "she'll've": "she will have", "she's": "she is", "should've": "should have", "shouldn't": "should not", "shouldn't've": "should not have",
                       "so've": "so have", "so's": "so as", "this's": "this is", "that'd": "that would", "that'd've": "that would have", "that's": "that is",
                       "there'd": "there would", "there'd've": "there would have", "there's": "there is", "here's": "here is", "they'd": "they would",
                       "they'd've": "they would have", "they'll": "they will", "they'll've": "they will have", "they're": "they are", "they've": "they have",
                       "to've": "to have", "wasn't": "was not", "we'd": "we would", "we'd've": "we would have", "we'll": "we will", "we'll've": "we will have",
                       "we're": "we are", "we've": "we have", "weren't": "were not", "what'll": "what will", "what'll've": "what will have",
                       "what're": "what are",  "what's": "what is", "what've": "what have", "when's": "when is", "when've": "when have", "where'd": "where did",
                       "where's": "where is", "where've": "where have", "who'll": "who will", "who'll've": "who will have", "who's": "who is",
                       "who've": "who have", "why's": "why is", "why've": "why have", "will've": "will have", "won't": "will not", "won't've": "will not have",
                       "would've": "would have", "wouldn't": "would not", "wouldn't've": "would not have", "y'all": "you all", "y'all'd": "you all would",
                       "y'all'd've": "you all would have", "y'all're": "you all are", "y'all've": "you all have", "you'd": "you would", "you'd've": "you would have",
                       "you'll": "you will", "you'll've": "you will have", "you're": "you are", "you've": "you have", 'u.s': 'america', 'e.g': 'for example'}

punct = [',', '.', '"', ':', ')', '(', '-', '!', '?', '|', ';', "'", '$', '&', '/', '[', ']', '>', '%', '=', '#', '*', '+', '\\', '•',  '~', '@', '£',
         '·', '_', '{', '}', '©', '^', '®', '`',  '<', '→', '°', '€', '™', '›',  '♥', '←', '×', '§', '″', '′', 'Â', '█', '½', 'à', '…',
         '“', '★', '”', '–', '●', 'â', '►', '−', '¢', '²', '¬', '░', '¶', '↑', '±', '¿', '▾', '═', '¦', '║', '―', '¥', '▓', '—', '‹', '─',
         '▒', '：', '¼', '⊕', '▼', '▪', '†', '■', '’', '▀', '¨', '▄', '♫', '☆', 'é', '¯', '♦', '¤', '▲', 'è', '¸', '¾', 'Ã', '⋅', '‘', '∞',
         '∙', '）', '↓', '、', '│', '（', '»', '，', '♪', '╩', '╚', '³', '・', '╦', '╣', '╔', '╗', '▬', '❤', 'ï', 'Ø', '¹', '≤', '‡', '√', ]

punct_mapping = {"‘": "'", "₹": "e", "´": "'", "°": "", "€": "e", "™": "tm", "√": " sqrt ", "×": "x", "²": "2", "—": "-", "–": "-", "’": "'", "_": "-",
                 "`": "'", '“': '"', '”': '"', '“': '"', "£": "e", '∞': 'infinity', 'θ': 'theta', '÷': '/', 'α': 'alpha', '•': '.', 'à': 'a', '−': '-',
                 'β': 'beta', '∅': '', '³': '3', 'π': 'pi', '!': ' '}


def clean_text(text):
    '''Make text lowercase, remove text in square brackets, remove links, remove punctuation,
    and remove words containing numbers.'''
    text = re.sub(r'\:(.*?)\:', '', text)
    text = str(text).lower()  # Making Text Lowercase
    text = re.sub('\[.*?\]', '', text)
    # The next 2 lines remove html text
    text = BeautifulSoup(text, 'lxml').get_text()
    text = re.sub('https?://\S+|www\.\S+', '', text)
    text = re.sub('<.*?>+', '', text)
    text = re.sub('\n', '', text)
    text = re.sub('\w*\d\w*', '', text)
    # replacing everything with space except (a-z, A-Z, ".", "?", "!", ",", "'")
    text = re.sub(r"[^a-zA-Z?.!,¿']+", " ", text)
    return text


def clean_contractions(text, mapping):
    '''Clean contraction using contraction mapping'''
    specials = ["’", "‘", "´", "`"]
    for s in specials:
        text = text.replace(s, "'")
    for word in mapping.keys():
        if "" + word + "" in text:
            text = text.replace("" + word + "", "" + mapping[word] + "")
    # Remove Punctuations
    text = re.sub('[%s]' % re.escape(string.punctuation), '', text)
    # creating a space between a word and the punctuation following it
    # eg: "he is a boy." => "he is a boy ."
    text = re.sub(r"([?.!,¿])", r" \1 ", text)
    text = re.sub(r'[" "]+', " ", text)
    return text


def clean_special_chars(text, punct, mapping):
    '''Cleans special characters present (if any)'''
    for p in mapping:
        text = text.replace(p, mapping[p])

    for p in punct:
        text = text.replace(p, f' {p} ')

    specials = {'\u200b': ' ', '…': ' ... ',
                '\ufeff': '', 'करना': '', 'है': ''}
    for s in specials:
        text = text.replace(s, specials[s])

    return text


def remove_space(text):
    '''Removes awkward spaces'''
    # Removes awkward spaces
    text = text.strip()
    text = text.split()
    return " ".join(text)


def preprocess_text(text):
    '''Cleaning and parsing the text.'''
    text = clean_text(text)
    text = clean_contractions(text, contraction_mapping)
    text = clean_special_chars(text, punct, punct_mapping)
    text = remove_space(text)
    return text