The Basics Of Natural Language Processing in 10 Minutes

pip install nltk

import nltk
from nltk.tokenize import sent_tokenize,word_tokenize
example_text = "Hello there, how are you doing today? The weather is great today. The sky is blue. python is awsome"
print(sent_tokenize(example_text))
print(word_tokenize(example_text))

##sent_tokenize (Separated by sentence)
['Hello there, how are you doing today?', 'The weather is great today.', 'The sky is blue.', 'python is awsome']
##word_tokenize (Separated by words)
['Hello', 'there', ',', 'how', 'are', 'you', 'doing', 'today', '?', 'The', 'weather', 'is', 'great', 'today', '.', 'The', 'sky', 'is', 'blue', '.', 'python', 'is', 'awsome']

from nltk.corpus import stopwords
print(stopwords.words('english'))
######################
######OUTPUT##########
######################
['i', 'me', 'my', 'myself', 'we', 'our', 'ours', 'ourselves', 'you', "you're", "you've", "you'll", "you'd", 'your', 'yours', 'yourself', 'yourselves', 'he', 'him', 'his', 'himself', 'she', "she's", 'her', 'hers', 'herself', 'it', "it's", 'its', 'itself', 'they', 'them', 'their', 'theirs', 'themselves', 'what', 'which', 'who', 'whom', 'this', 'that', "that'll", 'these', 'those', 'am', 'is', 'are', 'was', 'were', 'be', 'been', 'being', 'have', 'has', 'had', 'having', 'do', 'does', 'did', 'doing', 'a', 'an', 'the', 'and', 'but', 'if', 'or', 'because', 'as', 'until', 'while', 'of', 'at', 'by', 'for', 'with', 'about', 'against', 'between', 'into', 'through', 'during', 'before', 'after', 'above', 'below', 'to', 'from', 'up', 'down', 'in', 'out', 'on', 'off', 'over', 'under', 'again', 'further', 'then', 'once', 'here', 'there', 'when', 'where', 'why', 'how', 'all', 'any', 'both', 'each', 'few', 'more', 'most', 'other', 'some', 'such', 'no', 'nor', 'not', 'only', 'own', 'same', 'so', 'than', 'too', 'very', 's', 't', 'can', 'will', 'just', 'don', "don't", 'should', "should've", 'now', 'd', 'll', 'm', 'o', 're', 've', 'y', 'ain', 'aren', "aren't", 'couldn', "couldn't", 'didn', "didn't", 'doesn', "doesn't", 'hadn', "hadn't", 'hasn', "hasn't", 'haven', "haven't", 'isn', "isn't", 'ma', 'mightn', "mightn't", 'mustn', "mustn't", 'needn', "needn't", 'shan', "shan't", 'shouldn', "shouldn't", 'wasn', "wasn't", 'weren', "weren't", 'won', "won't", 'wouldn', "wouldn't"]

from nltk.corpus import stopwords
text = 'he is a good boy. he is very good in coding'
text = word_tokenize(text)
text_with_no_stopwords = [word for word in text if word not in stopwords.words('english')]
text_with_no_stopwords
##########OUTPUT##########
['good', 'boy', '.', 'good', 'coding']

from nltk.stem import PorterStemmer
ps = PorterStemmer()    ## Creating an object for porterstemmer
example_words = ['earn',"earning","earned","earns"]  ##Example words
for w in example_words:
    print(ps.stem(w))    ##Using ps object stemming the word
##########OUTPUT##########
earn
earn
earn
earn
Here we can see that earning,earned and earns are stem to there lemma or root word earn.

from nltk.stem import WordNetLemmatizer
lemmatizer = WordNetLemmatizer() ## Create object for lemmatizer
example_words = ['history','formality','changes']
for w in example_words:
    print(lemmatizer.lemmatize(w))
#########OUTPUT############
----Lemmatizer-----
history
formality
change
-----Stemming------
histori
formal
chang

from nltk.corpus import wordnet
synonyms = []   ## Creaing an empty list for all the synonyms
antonyms =[]    ## Creaing an empty list for all the antonyms
for syn in wordnet.synsets("happy"): ## Giving word 
    for i in syn.lemmas():        ## Finding the lemma,matching 
        synonyms.append(i.name())  ## appending all the synonyms       
        if i.antonyms():
            antonyms.append(i.antonyms()[0].name()) ## antonyms
print(set(synonyms)) ## Converting them into set for unique values
print(set(antonyms))
#########OUTPUT##########
{'felicitous', 'well-chosen', 'happy', 'glad'}
{'unhappy'}

 CC coordinating conjunction
 CD cardinal digit
 DT determiner
 EX existential there (like: “there is” … think of it like “there”)
 FW foreign word
 IN preposition/subordinating conjunction
 JJ adjective ‘big’
 JJR adjective, comparative ‘bigger’
 JJS adjective, superlative ‘biggest’
 LS list marker 1)
 MD modal could, will
 NN noun, singular ‘desk’
 NNS noun plural ‘desks’
 NNP proper noun, singular ‘Harrison’
 NNPS proper noun, plural ‘Americans’
 PDT predeterminer ‘all the kids’
 POS possessive ending parent’s
 PRP personal pronoun I, he, she
 PRP possessive pronoun my, his, hers
 RB adverb very, silently,
 RBR adverb, comparative better
 RBS adverb, superlative best
 RP particle give up
 TO to go ‘to’ the store.
 UH interjection errrrrrrrm
 VB verb, base form take
 VBD verb, past tense took
 VBG verb, gerund/present participle taking
 VBN verb, past participle taken
 VBP verb, sing. present, non-3d take
 VBZ verb, 3rd person sing. present takes
 WDT wh-determiner which
 WP wh-pronoun who, what
 WP possessive wh-pronoun whose
 WRB wh-abverb where, when

import nltk
nltk.download('averaged_perceptron_tagger')
sample_text = '''
An sincerity so extremity he additions. Her yet there truth merit. Mrs all projecting favourable now unpleasing. Son law garden chatty temper. Oh children provided to mr elegance marriage strongly. Off can admiration prosperous now devonshire diminution law.
'''
from nltk.tokenize import word_tokenize
words = word_tokenize(sample_text)
print(nltk.pos_tag(words))
################OUTPUT############
[('An', 'DT'), ('sincerity', 'NN'), ('so', 'RB'), ('extremity', 'NN'), ('he', 'PRP'), ('additions', 'VBZ'), ('.', '.'), ('Her', 'PRP$'), ('yet', 'RB'), ('there', 'EX'), ('truth', 'NN'), ('merit', 'NN'), ('.', '.'), ('Mrs', 'NNP'), ('all', 'DT'), ('projecting', 'VBG'), ('favourable', 'JJ'), ('now', 'RB'), ('unpleasing', 'VBG'), ('.', '.'), ('Son', 'NNP'), ('law', 'NN'), ('garden', 'NN'), ('chatty', 'JJ'), ('temper', 'NN'), ('.', '.'), ('Oh', 'UH'), ('children', 'NNS'), ('provided', 'VBD'), ('to', 'TO'), ('mr', 'VB'), ('elegance', 'NN'), ('marriage', 'NN'), ('strongly', 'RB'), ('.', '.'), ('Off', 'CC'), ('can', 'MD'), ('admiration', 'VB'), ('prosperous', 'JJ'), ('now', 'RB'), ('devonshire', 'VBP'), ('diminution', 'NN'), ('law', 'NN'), ('.', '.')]

sent1 = he is a good boy
sent2 = she is a good girl
sent3 = boy and girl are good 
        |
        |
  After removal of stopwords , lematization or stemming
sent1 = good boy
sent2 = good girl
sent3 = boy girl good  
        | ### Now we will calculate the frequency for each word by
        |     calculating the occurrence of each word
word  frequency
good     3
boy      2
girl     2
         | ## Then according to their occurrence we assign o or 1 
         |    according to their occurrence in the sentence
         | ## 1 for present and 0 fot not present
         f1  f2   f3
        girl good boy   
sent1    0    1    1     
sent2    1    0    1
sent3    1    1    1
### After this we pass the vector form to machine learning model

import pandas as pd
sent = pd.DataFrame(['he is a good boy', 'she is a good girl', 'boy and girl are good'],columns=['text'])
corpus = []
for i in range(0,3):
    words = sent['text'][i]
    words  = word_tokenize(words)
    texts = [lemmatizer.lemmatize(word) for word in words if word not in set(stopwords.words('english'))]
    text = ' '.join(texts)
    corpus.append(text)
print(corpus)   #### Cleaned Data
from sklearn.feature_extraction.text import CountVectorizer
cv = CountVectorizer() ## Creating Object for CountVectorizer
X = cv.fit_transform(corpus).toarray()
X  ## Vectorize Form 
############OUTPUT##############
['good boy', 'good girl', 'boy girl good']
array([[1, 0, 1],
       [0, 1, 1],
       [1, 1, 1]], dtype=int64)