Open In Colab

Pydantic Extractor

Here we test out the capabilities of our PydanticProgramExtractor - being able to extract out an entire Pydantic object using an LLM (either a standard text completion LLM or a function calling LLM).

The advantage of this over using a “single” metadata extractor is that we can extract multiple entities with a single LLM call.


import nest_asyncio


import os
import openai
os.environ["OPENAI_API_KEY"] = "YOUR_API_KEY"
openai.api_key = os.getenv("OPENAI_API_KEY")

Setup the Pydantic Model

Here we define a basic structured schema that we want to extract. It contains:

  • entities: unique entities in a text chunk

  • summary: a concise summary of the text chunk

  • contains_number: whether the chunk contains numbers

This is obviously a toy schema. We’d encourage you to be creative about the type of metadata you’d want to extract!

from pydantic import BaseModel, Field
from typing import List
class NodeMetadata(BaseModel):
    """Node metadata."""

    entities: List[str] = Field(
        ..., description="Unique entities in this text chunk."
    summary: str = Field(
        ..., description="A concise summary of this text chunk."
    contains_number: bool = Field(
            "Whether the text chunk contains any numbers (ints, floats, etc.)"

Setup the Extractor

Here we setup the metadata extractor. Note that we provide the prompt template for visibility into what’s going on.

from llama_index.program.openai_program import OpenAIPydanticProgram
from llama_index.extractors import PydanticProgramExtractor

Here is the content of the section:
Given the contextual information, extract out a {class_name} object.\

openai_program = OpenAIPydanticProgram.from_defaults(
    # extract_template_str=EXTRACT_TEMPLATE_STR

program_extractor = PydanticProgramExtractor(
    program=openai_program, input_key="input", show_progress=True

Load in Data

We load in Eugene’s essay ( using our LlamaHub SimpleWebPageReader.

# load in blog

from llama_hub.web.simple_web.base import SimpleWebPageReader
from llama_index.node_parser import SentenceSplitter

reader = SimpleWebPageReader(html_to_text=True)
docs = reader.load_data(urls=[""])
from llama_index.ingestion import IngestionPipeline

node_parser = SentenceSplitter(chunk_size=1024)

pipeline = IngestionPipeline(transformations=[node_parser, program_extractor])

orig_nodes =

Extract Metadata

Now that we’ve setup the metadata extractor and the data, we’re ready to extract some metadata!

We see that the pydantic feature extractor is able to extract all metadata from a given chunk in a single LLM call.

sample_entry = program_extractor.extract(orig_nodes[0:1])[0]
{'entities': ['eugeneyan', 'HackerNews', 'Karpathy'],
 'summary': 'This section discusses practical patterns for integrating large language models (LLMs) into systems & products. It introduces seven key patterns and provides information on evaluations and benchmarks in the field of language modeling.',
 'contains_number': True}
new_nodes = program_extractor.process_nodes(orig_nodes)