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# Graph QA

This notebook goes over how to do question answering over a graph data structure.

## Create the graph

In this section, we construct an example graph. At the moment, this works best for small pieces of text.

    from langchain.indexes import GraphIndexCreator
    from langchain.llms import OpenAI
    from langchain.document_loaders import TextLoader

    index_creator = GraphIndexCreator(llm=OpenAI(temperature=0))

    with open("../../state_of_the_union.txt") as f:
        all_text = f.read()

We will use just a small snippet, because extracting the knowledge triplets is a bit intensive at the moment.

    text = "\n".join(all_text.split("\n\n")[105:108])

    text

    'It won’t look like much, but if you stop and look closely, you’ll see a “Field of dreams,” the ground on which America’s future will be built. \nThis is where Intel, the American company that helped build Silicon Valley, is going to build its $20 billion semiconductor “mega site”. \nUp to eight state-of-the-art factories in one place. 10,000 new good-paying jobs. '

    graph = index_creator.from_text(text)

We can inspect the created graph.

    graph.get_triples()

    [('Intel', '$20 billion semiconductor "mega site"', 'is going to build'),
     ('Intel', 'state-of-the-art factories', 'is building'),
     ('Intel', '10,000 new good-paying jobs', 'is creating'),
     ('Intel', 'Silicon Valley', 'is helping build'),
     ('Field of dreams',
      "America's future will be built",
      'is the ground on which')]

## Querying the graph

We can now use the graph QA chain to ask question of the graph

    from langchain.chains import GraphQAChain

    chain = GraphQAChain.from_llm(OpenAI(temperature=0), graph=graph, verbose=True)

    chain.run("what is Intel going to build?")

    > Entering new GraphQAChain chain...
    Entities Extracted:
     Intel
    Full Context:
    Intel is going to build $20 billion semiconductor "mega site"
    Intel is building state-of-the-art factories
    Intel is creating 10,000 new good-paying jobs
    Intel is helping build Silicon Valley

    > Finished chain.

    ' Intel is going to build a $20 billion semiconductor "mega site" with state-of-the-art factories, creating 10,000 new good-paying jobs and helping to build Silicon Valley.'

## Save the graph

We can also save and load the graph.

    graph.write_to_gml("graph.gml")

    from langchain.indexes.graph import NetworkxEntityGraph

    loaded_graph = NetworkxEntityGraph.from_gml("graph.gml")

    loaded_graph.get_triples()

    [('Intel', '$20 billion semiconductor "mega site"', 'is going to build'),
     ('Intel', 'state-of-the-art factories', 'is building'),
     ('Intel', '10,000 new good-paying jobs', 'is creating'),
     ('Intel', 'Silicon Valley', 'is helping build'),
     ('Field of dreams',
      "America's future will be built",
      'is the ground on which')]