Defining and Customizing Nodes

Nodes represent "chunks" of source Documents, whether that is a text chunk, an image, or more. They also contain metadata and relationship information with other nodes and index structures.

Nodes are a first-class citizen in LlamaIndex. You can choose to define Nodes and all its attributes directly. You may also choose to "parse" source Documents into Nodes through our NodeParser classes.

For instance, you can do

from llama_index.core.node_parser import SentenceSplitter

parser = SentenceSplitter()

nodes = parser.get_nodes_from_documents(documents)

You can also choose to construct Node objects manually and skip the first section. For instance,

from llama_index.core.schema import TextNode, NodeRelationship, RelatedNodeInfo

node1 = TextNode(text="<text_chunk>", id_="<node_id>")
node2 = TextNode(text="<text_chunk>", id_="<node_id>")
# set relationships
node1.relationships[NodeRelationship.NEXT] = RelatedNodeInfo(
    node_id=node2.node_id
)
node2.relationships[NodeRelationship.PREVIOUS] = RelatedNodeInfo(
    node_id=node1.node_id
)
nodes = [node1, node2]

The RelatedNodeInfo class can also store additional metadata if needed:

node2.relationships[NodeRelationship.PARENT] = RelatedNodeInfo(
    node_id=node1.node_id, metadata={"key": "val"}
)

Customizing the ID

Each node has an node_id property that is automatically generated if not manually specified. This ID can be used for a variety of purposes; this includes being able to update nodes in storage, being able to define relationships between nodes (through IndexNode), and more.

You can also get and set the node_id of any TextNode directly.

print(node.node_id)
node.node_id = "My new node_id!"