extend() — langchain Function Reference

Architecture documentation for the extend() function in graph.py from the langchain codebase.

Function python LangChainCore Runnables calls 4

Entity Profile

LangChainCore→ Runnables→ extend() — langchain Function Reference

Dependency Diagram

graph TD
  6764536f_15b8_5436_aa1a_53ff3f1956c2["extend()"]
  646f3bb5_a594_563e_cfbf_e18bdc9efb90["Graph"]
  6764536f_15b8_5436_aa1a_53ff3f1956c2 -->|defined in| 646f3bb5_a594_563e_cfbf_e18bdc9efb90
  06f839e9_c953_ef45_72b3_7929f39522ed["is_uuid()"]
  6764536f_15b8_5436_aa1a_53ff3f1956c2 -->|calls| 06f839e9_c953_ef45_72b3_7929f39522ed
  202074c8_de09_73dd_415c_edea3bae12f1["first_node()"]
  6764536f_15b8_5436_aa1a_53ff3f1956c2 -->|calls| 202074c8_de09_73dd_415c_edea3bae12f1
  6b97cc3d_1205_0325_4d44_e903570471b2["last_node()"]
  6764536f_15b8_5436_aa1a_53ff3f1956c2 -->|calls| 6b97cc3d_1205_0325_4d44_e903570471b2
  3db09069_0f77_1402_7f96_14d549abbd03["copy()"]
  6764536f_15b8_5436_aa1a_53ff3f1956c2 -->|calls| 3db09069_0f77_1402_7f96_14d549abbd03
  style 6764536f_15b8_5436_aa1a_53ff3f1956c2 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/core/langchain_core/runnables/graph.py lines 384–420

    def extend(
        self, graph: Graph, *, prefix: str = ""
    ) -> tuple[Node | None, Node | None]:
        """Add all nodes and edges from another graph.

        Note this doesn't check for duplicates, nor does it connect the graphs.

        Args:
            graph: The graph to add.
            prefix: The prefix to add to the node ids.

        Returns:
            A tuple of the first and last nodes of the subgraph.
        """
        if all(is_uuid(node.id) for node in graph.nodes.values()):
            prefix = ""

        def prefixed(id_: str) -> str:
            return f"{prefix}:{id_}" if prefix else id_

        # prefix each node
        self.nodes.update(
            {prefixed(k): v.copy(id=prefixed(k)) for k, v in graph.nodes.items()}
        )
        # prefix each edge's source and target
        self.edges.extend(
            [
                edge.copy(source=prefixed(edge.source), target=prefixed(edge.target))
                for edge in graph.edges
            ]
        )
        # return (prefixed) first and last nodes of the subgraph
        first, last = graph.first_node(), graph.last_node()
        return (
            first.copy(id=prefixed(first.id)) if first else None,
            last.copy(id=prefixed(last.id)) if last else None,
        )