How to preprocess the Document object

[UncIeRick]

Hello Langchain community,

I have been working with the Langchain project and currently facing a challenge regarding preprocessing the text inside the Document object.

Specifically, I want to extract and preprocess the content within, for example, the "page_content" field of the Document object. However, I haven't been able to locate a specific method or access point in the Langchain codebase to retrieve this information.
I would greatly appreciate it if anyone in the community could provide some insights or guidance on how to preprocess the texts. Are there any existing methods or techniques that I might have missed?

Additionally, if there are any alternative approaches or best practices for preprocessing text within Langchain, I would be interested in exploring those as well.

Thank you in advance for your help and suggestions. I'm looking forward to hearing from the community.

[dosubot[bot]]

Answer generated by a 🤖

Answer

I understand that you're working with the LangChain project and you're looking for a way to preprocess the text inside the Document object, specifically the "page_content" field. You're also interested in learning about any existing methods or best practices for this task within the LangChain framework.

Here's a potential solution to your problem. In LangChain, you can create a new class that inherits from the BaseDocumentTransformer abstract base class. Within this new class, you can implement the transform_documents and atransform_documents methods. These methods allow you to access and manipulate the page_content field of each Document object.

Here's an example of how you can do this:

from langchain.schema.document import Document, BaseDocumentTransformer
from typing import Any, Sequence

class PreprocessTransformer(BaseDocumentTransformer):
    def transform_documents(
        self, documents: Sequence[Document], **kwargs: Any
    ) -> Sequence[Document]:
        for document in documents:
            # Access the page_content field
            content = document.page_content
            # Apply your preprocessing steps here
            # For example, convert the content to lowercase
            document.page_content = content.lower()
        return documents

    async def atransform_documents(
        self, documents: Sequence[Document], **kwargs: Any
    ) -> Sequence[Document]:
        # Implement the asynchronous version of the method
        return self.transform_documents(documents, **kwargs)

In this example, the transform_documents method iterates over each Document in the provided sequence, accesses the page_content field, and converts the content to lowercase. The atransform_documents method simply calls the synchronous transform_documents method, but you could implement a different, asynchronous preprocessing logic if needed.

Please note that this is just one potential solution. Depending on your specific needs and the complexity of your preprocessing steps, you might need to adjust this approach.

If you find this solution helpful and believe it could be beneficial to others, I encourage you to make a pull request to update the LangChain documentation. This way, other users facing the same issue can benefit from your contribution.

Sources

• langchain/schema/document.py

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