deepset-ai--haystack/docs-website/versioned_docs/version-2.21/pipeline-components/rankers/huggingfaceteiranker.mdx

---
title: "HuggingFaceTEIRanker"
id: huggingfaceteiranker
slug: "/huggingfaceteiranker"
description: "Use this component to rank documents based on their similarity to the query using a Text Embeddings Inference (TEI) API endpoint."
---

# HuggingFaceTEIRanker

Use this component to rank documents based on their similarity to the query using a Text Embeddings Inference (TEI) API endpoint.

<div className="key-value-table">

|  |  |
| --- | --- |
| **Most common position in a pipeline** | In a query pipeline, after a component that returns a list of documents, such as a [Retriever](../retrievers.mdx) |
| **Mandatory init variables** | `url`: Base URL of the TEI reranking service (for example, "https://api.example.com"). |
| **Mandatory run variables** | `query`: A query string  <br /> <br />`documents`: A list of document objects |
| **Output variables** | `documents`: A grouped list of documents |
| **API reference** | [Rankers](/reference/rankers-api) |
| **GitHub link** | https://github.com/deepset-ai/haystack/blob/main/haystack/components/rankers/hugging_face_tei.py |

</div>

## Overview

HuggingFaceTEIRanker ranks documents based on semantic relevance to a specified query.

You can use it with one of the Text Embeddings Inference (TEI) API endpoints:

- [Self-hosted Text Embeddings Inference](https://github.com/huggingface/text-embeddings-inference)
- [Hugging Face Inference Endpoints](https://huggingface.co/inference-endpoints)

You can also specify the `top_k` parameter to set the maximum number of documents to return.

Depending on your TEI server configuration, you may also require a Hugging Face [token](https://huggingface.co/settings/tokens) to use for authorization. You can set it with `HF_API_TOKEN` or `HF_TOKEN` environment variables, or by using Haystack's [Secret management](../../concepts/secret-management.mdx).

## Usage

### On its own

You can use `HuggingFaceTEIRanker` outside of a pipeline to order documents based on your query.

This example uses the `HuggingFaceTEIRanker` to rank two simple documents. To run the Ranker, pass a query, provide the documents, and set the number of documents to return in the `top_k` parameter.

```python
from haystack import Document
from haystack.components.rankers import HuggingFaceTEIRanker
from haystack.utils import Secret

reranker = HuggingFaceTEIRanker(
    url="http://localhost:8080",
    top_k=5,
    timeout=30,
    token=Secret.from_token("my_api_token")
)

docs = [Document(content="The capital of France is Paris"), Document(content="The capital of Germany is Berlin")]

result = reranker.run(query="What is the capital of France?", documents=docs)

ranked_docs = result["documents"]
print(ranked_docs)
>> {'documents': [Document(id=..., content: 'the capital of France is Paris', score: 0.9979767),
>>                Document(id=..., content: 'the capital of Germany is Berlin', score: 0.13982213)]}
```

### In a pipeline

`HuggingFaceTEIRanker` is most efficient in query pipelines when used after a Retriever.

Below is an example of a pipeline that retrieves documents from an `InMemoryDocumentStore` based on keyword search (using `InMemoryBM25Retriever`). It then uses the `HuggingFaceTEIRanker` to rank the retrieved documents according to their similarity to the query. The pipeline uses the default settings of the Ranker.

```python
from haystack import Document, Pipeline
from haystack.document_stores.in_memory import InMemoryDocumentStore
from haystack.components.retrievers.in_memory import InMemoryBM25Retriever
from haystack.components.rankers import HuggingFaceTEIRanker

docs = [
    Document(content="Paris is in France"),
    Document(content="Berlin is in Germany"),
    Document(content="Lyon is in France"),
]
document_store = InMemoryDocumentStore()
document_store.write_documents(docs)

retriever = InMemoryBM25Retriever(document_store=document_store)
ranker = HuggingFaceTEIRanker(url="http://localhost:8080")
ranker.warm_up()

document_ranker_pipeline = Pipeline()
document_ranker_pipeline.add_component(instance=retriever, name="retriever")
document_ranker_pipeline.add_component(instance=ranker, name="ranker")

document_ranker_pipeline.connect("retriever.documents", "ranker.documents")

query = "Cities in France"
document_ranker_pipeline.run(
    data={
        "retriever": {"query": query, "top_k": 3},
        "ranker": {"query": query, "top_k": 2},
    },
)
```