What Is NLP?
Natural Language Processing (NLP) is the field of AI focused on enabling computers to understand, interpret, and generate human language. From search engines and virtual assistants to translation services and sentiment analysis, NLP powers many of the tools we use every day.
Text Preprocessing
Before feeding text into a model, it needs to be cleaned and transformed. Common preprocessing steps include:
import re
import nltk
from nltk.corpus import stopwords
from nltk.stem import WordNetLemmatizer
nltk.download('punkt', quiet=True)
nltk.download('stopwords', quiet=True)
nltk.download('wordnet', quiet=True)
def preprocess_text(text):
# Lowercase
text = text.lower()
# Remove special characters
text = re.sub(r'[^a-z\s]', '', text)
# Tokenize
tokens = text.split()
# Remove stopwords
stop_words = set(stopwords.words('english'))
tokens = [t for t in tokens if t not in stop_words]
# Lemmatize
lemmatizer = WordNetLemmatizer()
tokens = [lemmatizer.lemmatize(t) for t in tokens]
return ' '.join(tokens)
sample = "I'm loving the new features in this amazing update!"
print(preprocess_text(sample))
# Output: loving new features amazing update
Key NLP Techniques
Bag of Words and TF-IDF
The simplest way to convert text to numbers is the Bag of Words (BoW) approach, which counts word occurrences. Term Frequency–Inverse Document Frequency (TF-IDF) improves on this by downweighting common words.
from sklearn.feature_extraction.text import TfidfVectorizer
documents = [
"Machine learning is fascinating",
"Neural networks power modern AI",
"Natural language processing uses neural networks"
]
vectorizer = TfidfVectorizer()
tfidf_matrix = vectorizer.fit_transform(documents)
print(vectorizer.get_feature_names_out())
print(tfidf_matrix.toarray())
Word Embeddings
Embeddings map words to dense vectors where semantic relationships are preserved. Word2Vec, GloVe, and FastText are classic approaches that capture meaning — for example, king - man + woman ≈ queen.
Transformer Models
The 2017 "Attention Is All You Need" paper introduced transformers, which revolutionized NLP. Models like BERT, GPT, and their descendants understand context by attending to all words in a sequence simultaneously.
from transformers import pipeline
classifier = pipeline("sentiment-analysis")
result = classifier("I love learning about artificial intelligence!")
print(result)
# [{'label': 'POSITIVE', 'score': 0.9998}]
Common NLP Tasks
- Text Classification: Spam detection, topic labeling
- Named Entity Recognition: Identifying people, places, organizations
- Machine Translation: Converting text between languages
- Text Generation: Summarization, dialogue systems
- Sentiment Analysis: Determining emotional tone
Conclusion
NLP has evolved from simple keyword matching to understanding nuanced human language. The rise of pre-trained transformer models has made powerful NLP accessible to anyone with a few lines of code. Whether you're building a chatbot or analyzing customer feedback, the tools are ready — you just need to start experimenting.
