Pralekha: Cross-Lingual Document Alignment for Indic Languages

Overview

PRALEKHA is a large-scale document-level benchmark for Cross-Lingual Document Alignment (CLDA) evaluation, comprising over 3 million aligned document pairs across 11 Indic languages and English, with 1.5 million being English-Indic pairs. We propose a comprehensive evaluation framework that introduces Document Alignment Coefficient (DAC), a novel metric specifically designed for fine-grained document alignment. Unlike existing approaches that use pooled document-level embeddings, DAC aligns smaller chunks within documents and computes similarity based on the ratio of aligned chunks. This method outperforms baseline pooling approaches, particularly in noisy scenarios, yielding 15–20% precision and 5–10% F1 score improvements.

Usage

1. Setup

Follow these steps to set up the environment and get started with the pipeline:

i. Clone the Repository

Clone this repository to your local system:

git clone https://github.com/AI4Bharat/Pralekha.git
cd Pralekha

ii. Set Up a Conda Environment

Create and activate a new Conda environment for this project:

conda create -n pralekha python=3.9 -y
conda activate pralekha

iii. Install Dependencies

Install the required Python packages:

pip install -r requirements.txt

2. Input Directory Structure

The pipeline expects a directory structure in the following format:

• A main directory containing language subdirectories named using their 3-letter ISO codes (e.g., eng for English, hin for Hindi, tam for Tamil, etc.)
• Each language subdirectory will contain .txt documents named in the format {doc_id}.txt, where doc_id serves as the unique identifier for each document.

Below is an example of the expected directory structure:

data/
├── eng/
│   ├── tech-innovations-2023.txt                
│   ├── sports-highlights-day5.txt     
│   ├── press-release-456.txt         
│   ├── ...
├── hin/
│   ├── daily-briefing-april.txt       
│   ├── market-trends-yearend.txt      
│   ├── इंडिया-न्यूज़123.txt              
│   ├── ...
├── tam/
│   ├── kollywood-review-movie5.txt   
│   ├── 2023-pilgrimage-guide.txt       
│   ├── கடலோர-மாநில-செய்தி.txt          
│   ├── ...
...

3. Split Documents into Granular Shards

To process documents into granular shards, use the doc2granular-shards.sh script.

This script splits documents into chunks of varying granularities:

• G = 1 → Sentence-level
• G = 2, 4, 8 → Chunk-level (2, 4, or 8 sentences per chunk)

Run the script:

bash doc2granular-shards.sh

4. Create Embeddings

Generate embeddings for your dataset using one of the two supported models: LaBSE or SONAR.

bash create_embeddings.sh

Choose the desired model by editing the script as needed. Both models can be run sequentially or independently by enabling/disabling the respective sections.

5. Run the Pipeline

The final step is to execute the pipeline based on your chosen method:

For baseline approaches:

bash run_baseline_pipeline.sh

For the proposed DAC approach:

bash run_dac_pipeline.sh

Each pipeline comes with a variety of configurable parameters, allowing you to tailor the process to your specific requirements. Please review and edit the scripts as needed before running to ensure they align with your desired configurations.

License

This dataset is released under the CC BY 4.0 license.

Citation

If you use Pralekha in your work, please cite us:

@misc{suryanarayanan2025pralekhacrosslingualdocumentalignment,
      title={Pralekha: Cross-Lingual Document Alignment for Indic Languages}, 
      author={Sanjay Suryanarayanan and Haiyue Song and Mohammed Safi Ur Rahman Khan and Anoop Kunchukuttan and Raj Dabre},
      year={2025},
      eprint={2411.19096},
      archivePrefix={arXiv},
      primaryClass={cs.CL},
      url={https://arxiv.org/abs/2411.19096}, 
}

Contact

For any questions or feedback, please contact:

• Raj Dabre (raj.dabre@cse.iitm.ac.in)
• Sanjay Suryanarayanan (sanj.ai@outlook.com)
• Haiyue Song (haiyue.song@nict.go.jp)
• Mohammed Safi Ur Rahman Khan (safikhan2000@gmail.com)

Please get in touch with us for any copyright concerns.