trim_last_node() — langchain Function Reference

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

Function python LangChainCore Runnables calls 3

Entity Profile

LangChainCore→ Runnables→ trim_last_node() — langchain Function Reference

Dependency Diagram

graph TD
  5ce5505c_4a08_f190_13f7_65b75fa4fde9["trim_last_node()"]
  646f3bb5_a594_563e_cfbf_e18bdc9efb90["Graph"]
  5ce5505c_4a08_f190_13f7_65b75fa4fde9 -->|defined in| 646f3bb5_a594_563e_cfbf_e18bdc9efb90
  6b97cc3d_1205_0325_4d44_e903570471b2["last_node()"]
  5ce5505c_4a08_f190_13f7_65b75fa4fde9 -->|calls| 6b97cc3d_1205_0325_4d44_e903570471b2
  1eb728cf_7631_9204_a3a2_e3d486989562["remove_node()"]
  5ce5505c_4a08_f190_13f7_65b75fa4fde9 -->|calls| 1eb728cf_7631_9204_a3a2_e3d486989562
  6607eba9_2327_f10b_2f7a_81bdd9ce1d84["_last_node()"]
  5ce5505c_4a08_f190_13f7_65b75fa4fde9 -->|calls| 6607eba9_2327_f10b_2f7a_81bdd9ce1d84
  style 5ce5505c_4a08_f190_13f7_65b75fa4fde9 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/core/langchain_core/runnables/graph.py lines 494–505

    def trim_last_node(self) -> None:
        """Remove the last node if it exists and has a single incoming edge.

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