trim_first_node() — langchain Function Reference

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

Function python LangChainCore Runnables calls 3

Entity Profile

LangChainCore→ Runnables→ trim_first_node() — langchain Function Reference

Dependency Diagram

graph TD
  600fa640_4465_baee_3ef3_0c1fda5bf94b["trim_first_node()"]
  646f3bb5_a594_563e_cfbf_e18bdc9efb90["Graph"]
  600fa640_4465_baee_3ef3_0c1fda5bf94b -->|defined in| 646f3bb5_a594_563e_cfbf_e18bdc9efb90
  202074c8_de09_73dd_415c_edea3bae12f1["first_node()"]
  600fa640_4465_baee_3ef3_0c1fda5bf94b -->|calls| 202074c8_de09_73dd_415c_edea3bae12f1
  1eb728cf_7631_9204_a3a2_e3d486989562["remove_node()"]
  600fa640_4465_baee_3ef3_0c1fda5bf94b -->|calls| 1eb728cf_7631_9204_a3a2_e3d486989562
  c2fe47ba_c1ff_8826_55de_cd87be044850["_first_node()"]
  600fa640_4465_baee_3ef3_0c1fda5bf94b -->|calls| c2fe47ba_c1ff_8826_55de_cd87be044850
  style 600fa640_4465_baee_3ef3_0c1fda5bf94b fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/core/langchain_core/runnables/graph.py lines 481–492

    def trim_first_node(self) -> None:
        """Remove the first node if it exists and has a single outgoing edge.

        i.e., if removing it would not leave the graph without a "first" node.
        """
        first_node = self.first_node()
        if (
            first_node
            and _first_node(self, exclude=[first_node.id])
            and len({e for e in self.edges if e.source == first_node.id}) == 1
        ):
            self.remove_node(first_node)