README.md

---
license: llama2
---


# RepLLaMA-7B-Passage-MRL

[Fine-Tuning LLaMA for Multi-Stage Text Retrieval](https://arxiv.org/abs/2310.08319).
Xueguang Ma, Liang Wang, Nan Yang, Furu Wei, Jimmy Lin, arXiv 2023

This model is fine-tuned from LLaMA-2-7B using LoRA and the embedding size is **flexible**, as Matryoshka Representation Learning is applied during training. The maximum dimensionality of query and passage embedding is 4096.

## Training Data
The model is fine-tuned on the training split of [MS MARCO Passage Ranking](https://microsoft.github.io/msmarco/Datasets) datasets for 1 epoch.
Please check our paper for details.

## Usage

Below is an example to encode a query and a passage, and then compute their similarity using their embedding.

```python
import torch
from transformers import AutoModel, AutoTokenizer

# Load the tokenizer and model
tokenizer = AutoTokenizer.from_pretrained('meta-llama/Llama-2-7b-hf')
model = AutoModel.from_pretrained('castorini/repllama-v1-mrl-7b-lora-passage')
dim = 512

# Define query and passage inputs
query = "What is llama?"
title = "Llama"
passage = "The llama is a domesticated South American camelid, widely used as a meat and pack animal by Andean cultures since the pre-Columbian era."
query_input = tokenizer(f'query: {query}</s>', return_tensors='pt')
passage_input = tokenizer(f'passage: {title} {passage}</s>', return_tensors='pt')

# Run the model forward to compute embeddings and query-passage similarity score
with torch.no_grad():
    # compute query embedding
    query_outputs = model(**query_input)
    query_embedding = query_outputs.last_hidden_state[0][-1][:dim]
    query_embedding = torch.nn.functional.normalize(query_embedding, p=2, dim=0)

    # compute passage embedding
    passage_outputs = model(**passage_input)
    passage_embeddings = passage_outputs.last_hidden_state[0][-1][:dim]
    passage_embeddings = torch.nn.functional.normalize(passage_embeddings, p=2, dim=0)

    # compute similarity score
    score = torch.dot(query_embedding, passage_embeddings)
    print(score)

```
## Batch inference and training
An unofficial replication of the inference and training code can be found [here](https://github.com/texttron/tevatron/tree/main/examples/repllama)

## Citation

If you find our paper or models helpful, please consider cite as follows:

```
@article{rankllama,
      title={Fine-Tuning LLaMA for Multi-Stage Text Retrieval}, 
      author={Xueguang Ma and Liang Wang and Nan Yang and Furu Wei and Jimmy Lin},
      year={2023},
      journal={arXiv:2310.08319},
}
```