Documentation: Langchain Integration (#1297)

Integration doc update
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Raghav Dixit
2024-05-13 10:19:33 -04:00
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@@ -13,7 +13,7 @@ Get started using these examples and quick links.
| Integrations | |
|---|---:|
| <h3> LlamaIndex </h3>LlamaIndex is a simple, flexible data framework for connecting custom data sources to large language models. Llama index integrates with LanceDB as the serverless VectorDB. <h3>[Lean More](https://gpt-index.readthedocs.io/en/latest/examples/vector_stores/LanceDBIndexDemo.html) </h3> |<img src="../assets/llama-index.jpg" alt="image" width="150" height="auto">|
| <h3>Langchain</h3>Langchain allows building applications with LLMs through composability <h3>[Lean More](https://python.langchain.com/docs/integrations/vectorstores/lancedb) | <img src="../assets/langchain.png" alt="image" width="150" height="auto">|
| <h3>Langchain</h3>Langchain allows building applications with LLMs through composability <h3>[Lean More](https://lancedb.github.io/lancedb/integrations/langchain/) | <img src="../assets/langchain.png" alt="image" width="150" height="auto">|
| <h3>Langchain TS</h3> Javascript bindings for Langchain. It integrates with LanceDB's serverless vectordb allowing you to build powerful AI applications through composibility using only serverless functions. <h3>[Learn More]( https://js.langchain.com/docs/modules/data_connection/vectorstores/integrations/lancedb) | <img src="../assets/langchain.png" alt="image" width="150" height="auto">|
| <h3>Voxel51</h3> It is an open source toolkit that enables you to build better computer vision workflows by improving the quality of your datasets and delivering insights about your models.<h3>[Learn More](./voxel51.md) | <img src="../assets/voxel.gif" alt="image" width="150" height="auto">|
| <h3>PromptTools</h3> Offers a set of free, open-source tools for testing and experimenting with models, prompts, and configurations. The core idea is to enable developers to evaluate prompts using familiar interfaces like code and notebooks. You can use it to experiment with different configurations of LanceDB, and test how LanceDB integrates with the LLM of your choice.<h3>[Learn More](./prompttools.md) | <img src="../assets/prompttools.jpeg" alt="image" width="150" height="auto">|

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# Langchain
<!-- ![Illustration](../assets/langchain.png) -->
<img src="../assets/langchain.png" alt="image" width="500" height="auto">|
## Quick Start
You can load your document data using langchain's loaders, for this example we are using `TextLoader` and `OpenAIEmbeddings` as the embedding model.
```python
import os
from langchain.document_loaders import TextLoader
from langchain.vectorstores import LanceDB
from langchain_openai import OpenAIEmbeddings
from langchain_text_splitters import CharacterTextSplitter
os.environ["OPENAI_API_KEY"] = "sk-..."
loader = TextLoader("../../modules/state_of_the_union.txt") # Replace with your data path
documents = loader.load()
documents = CharacterTextSplitter().split_documents(documents)
embeddings = OpenAIEmbeddings()
docsearch = LanceDB.from_documents(documents, embeddings)
query = "What did the president say about Ketanji Brown Jackson"
docs = docsearch.similarity_search(query)
print(docs[0].page_content)
```
## Documentation
In the above example `LanceDB` vector store class object is created using `from_documents()` method which is a `classmethod` and returns the initialized class object. You can also use `LanceDB.from_texts(texts: List[str],embedding: Embeddings)` class method.
The exhaustive list of parameters for `LanceDB` vector store are :
- `connection`: (Optional) `lancedb.db.LanceDBConnection` connection object to use. If not provided, a new connection will be created.
- `embedding`: Langchain embedding model.
- `vector_key`: (Optional) Column name to use for vector's in the table. Defaults to `vector`.
- `id_key`: (Optional) Column name to use for id's in the table. Defaults to `id`.
- `text_key`: (Optional) Column name to use for text in the table. Defaults to `text`.
- `table_name`: (Optional) Name of your table in the database. Defaults to `vectorstore`.
- `api_key`: (Optional) API key to use for LanceDB cloud database. Defaults to None.
- `region`: (Optional) Region to use for LanceDB cloud database. Only for LanceDB Cloud. Defaults to None.
- `mode`: (Optional) Mode to use for adding data to the table. Defaults to `overwrite`.
```python
db_url = "db://lang_test" # url of db you created
api_key = "xxxxx" # your API key
region="us-east-1-dev" # your selected region
vector_store = LanceDB(
uri=db_url,
api_key=api_key, #(dont include for local API)
region=region, #(dont include for local API)
embedding=embeddings,
table_name='langchain_test' #Optional
)
```
### Methods
To add texts and store respective embeddings automatically:
##### add_texts()
- `texts`: `Iterable` of strings to add to the vectorstore.
- `metadatas`: Optional `list[dict()]` of metadatas associated with the texts.
- `ids`: Optional `list` of ids to associate with the texts.
```python
vector_store.add_texts(texts = ['test_123'], metadatas =[{'source' :'wiki'}])
#Additionaly, to explore the table you can load it into a df or save it in a csv file:
tbl = vector_store.get_table()
print("tbl:", tbl)
pd_df = tbl.to_pandas()
pd_df.to_csv("docsearch.csv", index=False)
# you can also create a new vector store object using an older connection object:
vector_store = LanceDB(connection=tbl, embedding=embeddings)
```
For index creation make sure your table has enough data in it. An ANN index is ususally not needed for datasets ~100K vectors. For large-scale (>1M) or higher dimension vectors, it is beneficial to create an ANN index.
##### create_index()
- `col_name`: `Optional[str] = None`
- `vector_col`: `Optional[str] = None`
- `num_partitions`: `Optional[int] = 256`
- `num_sub_vectors`: `Optional[int] = 96`
- `index_cache_size`: `Optional[int] = None`
```python
# for creating vector index
vector_store.create_index(vector_col='vector', metric = 'cosine')
# for creating scalar index(for non-vector columns)
vector_store.create_index(col_name='text')
```

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@@ -8,6 +8,7 @@ excluded_globs = [
"../src/embedding.md",
"../src/examples/*.md",
"../src/integrations/voxel51.md",
"../src/integrations/langchain.md",
"../src/guides/tables.md",
"../src/python/duckdb.md",
"../src/embeddings/*.md",