Method _simplify_down

dask/_expr.py:1232–1272

(self)

        return iter(self.operands)

    def _simplify_down(self):
        from dask.highlevelgraph import HighLevelGraph

        issue_warning = False
        hlgs = []
        if any(
            isinstance(op, (HLGExpr, HLGFinalizeCompute, dict)) for op in self.operands
        ):
            for op in self.operands:
                if isinstance(op, (HLGExpr, HLGFinalizeCompute)):
                    hlgs.append(op)
                elif isinstance(op, dict):
                    hlgs.append(
                        HLGExpr(
                            dsk=HighLevelGraph.from_collections(
                                str(id(op)), op, dependencies=()
                            )
                        )
                    )
                else:
                    issue_warning = True
                    opt = op.optimize()
                    hlgs.append(
                        HLGExpr(
                            dsk=HighLevelGraph.from_collections(
                                opt._name, opt.__dask_graph__(), dependencies=()
                            )
                        )
                    )
        if issue_warning:
            warnings.warn(
                "Computing mixed collections that are backed by "
                "HighlevelGraphs/dicts and Expressions. "
                "This forces Expressions to be materialized. "
                "It is recommended to use only one type and separate the dask."
                "compute calls if necessary.",
                UserWarning,
            )
        if not hlgs:
            return None
        return _HLGExprSequence(*hlgs)


class _AnnotationsTombstone: ...