Next Word Predictor

Anirudha Belligundu
January 13, 2026

The Objective

Goal: Build a predictive text model similar to those used in mobile keyboards (like SwiftKey).

The Problem:

  • Typing on mobile devices can be slow and error-prone.
  • Predictive text algorithms improve user experience by suggesting the most likely next word.

The Solution:

  • An interactive Shiny Application that takes user text input.
  • Predicts the next word using Natural Language Processing (NLP) techniques.
  • Built on a large corpus of English text (Blogs, News, Twitter).

The Algorithm & Data

Data Processing:

  • Source: HC Corpora Dataset (English).
  • Cleaning: Text was converted to lowercase, punctuation removed, and tokenized.
  • N-Grams: We generated Bigrams (2-word combos) and Trigrams (3-word combos).

Prediction Logic (Backoff Model):

  1. Input: The app reads the last few words of the user's sentence.
  2. Search: It first looks for a match in the Trigram dataset (high precision).
  3. Backoff: If no Trigram match is found, it “backs off” to the Bigram dataset.
  4. Default: If no match is found, it returns a common word (e.g., “the”).

How the App Works

The User Interface is designed for simplicity:

  1. Input Field: Users type a phrase into the text box (e.g., “I want to”).
  2. Reactive Output: As the user types, the algorithm instantly processes the text.
  3. Result: The predicted next word appears on the right side of the screen.

Key Features:

  • Fast response time (optimized data structures).
  • Handles unknown words gracefully using the Backoff method.
  • Real-time feedback.

Performance & Conclusion

Summary: The “Next Word Predictor” successfully demonstrates the power of N-gram language models in a lightweight Shiny application.

Limitations:

  • Memory constraints required sampling only a portion of the original dataset.
  • Does not handle long-term context (beyond 2-3 words).

Future Improvements:

  • Implement a larger dictionary with more memory-efficient storage (e.g., hash tables).
  • Add support for 4-grams (Quadgrams) for better accuracy.
  • Improve handling of swear words and foreign characters.

App Link: https://anirudha-belligundu.shinyapps.io/NextWordPredictor/