# doc2query/all-t5-base-v1

This is a doc2query model based on T5 (also known as docT5query).

It can be used for:

• Document expansion: You generate for your paragraphs 20-40 queries and index the paragraphs and the generates queries in a standard BM25 index like Elasticsearch, OpenSearch, or Lucene. The generated queries help to close the lexical gap of lexical search, as the generate queries contain synonyms. Further, it re-weights words giving important words a higher weight even if they appear seldomn in a paragraph. In our BEIR paper we showed that BM25+docT5query is a powerful search engine. In the BEIR repository we have an example how to use docT5query with Pyserini.
• Domain Specific Training Data Generation: It can be used to generate training data to learn an embedding model. On SBERT.net we have an example how to use the model to generate (query, text) pairs for a given collection of unlabeled texts. These pairs can then be used to train powerful dense embedding models.

## Usage

from transformers import T5Tokenizer, T5ForConditionalGeneration

model_name = 'doc2query/all-t5-base-v1'
tokenizer = T5Tokenizer.from_pretrained(model_name)
model = T5ForConditionalGeneration.from_pretrained(model_name)

text = "Python is an interpreted, high-level and general-purpose programming language. Python's design philosophy emphasizes code readability with its notable use of significant whitespace. Its language constructs and object-oriented approach aim to help programmers write clear, logical code for small and large-scale projects."

input_ids = tokenizer.encode(text, max_length=384, truncation=True, return_tensors='pt')
outputs = model.generate(
input_ids=input_ids,
max_length=64,
do_sample=True,
top_p=0.95,
num_return_sequences=5)

print("Text:")
print(text)

print("\nGenerated Queries:")
for i in range(len(outputs)):
query = tokenizer.decode(outputs[i], skip_special_tokens=True)
print(f'{i + 1}: {query}')


Note: model.generate() is non-deterministic. It produces different queries each time you run it.

## Training

This model fine-tuned google/t5-v1_1-base for 570k training steps. For the training script, see the train_script.py in this repository.

The input-text was truncated to 384 word pieces. Output text was generated up to 64 word pieces.

This model was trained on a large collection of datasets. For the exact datasets names and weights see the data_config.json in this repository. Most of the datasets are available at https://huggingface.co/sentence-transformers.

The datasets include besides others:

• (title, body) pairs from Reddit
• (title, body) pairs and (title, answer) pairs from StackExchange and Yahoo Answers!
• (title, review) pairs from Amazon reviews
• (query, paragraph) pairs from MS MARCO, NQ, and GooAQ
• (question, duplicate_question) from Quora and WikiAnswers
• (title, abstract) pairs from S2ORC

## Prefix

This model was trained without a prefix. In contrast to doc2query/all-with_prefix-t5-base-v1 you cannot specify what type of transformation (answer2question, review2title) etc. you will have. This can lead to a mixture of output values.