# Play with DingoDB using Langchain

Firstly, you should have a [DingoDB instance up and running](https://dingodb.readthedocs.io/en/latest/deployment/index.html).

```shell
pip install dingodb
or install latest:
pip install git+https://git@github.com/dingodb/pydingo.git
```
We want to use OpenAIEmbeddings so we have to get the OpenAI API Key.
```text
import os
import getpass

os.environ["OPENAI_API_KEY"] = getpass.getpass("OpenAI API Key:")
```

```text
OpenAI API Key:········
```
```text
from langchain.embeddings.openai import OpenAIEmbeddings
from langchain.text_splitter import CharacterTextSplitter
from langchain.vectorstores import Dingo
from langchain.document_loaders import TextLoader
```
```text
from langchain.document_loaders import TextLoader

loader = TextLoader("../../../state_of_the_union.txt")
documents = loader.load()
text_splitter = CharacterTextSplitter(chunk_size=1000, chunk_overlap=0)
docs = text_splitter.split_documents(documents)

embeddings = OpenAIEmbeddings()
```
```text
from dingodb import DingoDB

index_name = "langchain-demo"

dingo_client = DingoDB(user="", password="", host=["127.0.0.1:13000"])
# First, check if our index already exists. If it doesn't, we create it
if index_name not in dingo_client.get_index():
    # we create a new index, modify to your own
    dingo_client.create_index(
      index_name=index_name,
      dimension=1536,
      metric_type='cosine',
      auto_id=False
)

# The OpenAI embedding model `text-embedding-ada-002 uses 1536 dimensions`
docsearch = Dingo.from_documents(docs, embeddings, client=dingo_client, index_name=index_name)
```
```text
from langchain.embeddings.openai import OpenAIEmbeddings
from langchain.text_splitter import CharacterTextSplitter
from langchain.vectorstores import Dingo
from langchain.document_loaders import TextLoader
```
```text
query = "What did the president say about Ketanji Brown Jackson"
docs = docsearch.similarity_search(query)
```
```text
print(docs[0].page_content)
```

### Adding More Text to an Existing Index

More text can embedded and upserted to an existing Dingo index using the add_texts function.

```text
vectorstore = Dingo(embeddings, "text", client=dingo_client, index_name=index_name)

vectorstore.add_texts(["More text!"])
```

### Maximal Marginal Relevance Searches

In addition to using similarity search in the retriever object, you can also use mmr as retriever.
```text
retriever = docsearch.as_retriever(search_type="mmr")
matched_docs = retriever.get_relevant_documents(query)
for i, d in enumerate(matched_docs):
    print(f"\n## Document {i}\n")
    print(d.page_content)
```
Or use 'max_marginal_relevance_search' directly:
```text
found_docs = docsearch.max_marginal_relevance_search(query, k=2, fetch_k=10)
for i, doc in enumerate(found_docs):
    print(f"{i + 1}.", doc.page_content, "\n")
```