Method _lower

dask/dataframe/dask_expr/_shuffle.py:1162–1201

(self)

    ]

    def _lower(self):
        divisions = self.other._meta._constructor(self._divisions())
        partitions = _SetPartitionsPreSetIndex(self.other, divisions)
        assigned = Assign(self.frame, "_partitions", partitions)
        if isinstance(self._other, Expr):
            assigned = Assign(assigned, "_index", self._other)
        shuffled = Shuffle(
            assigned,
            "_partitions",
            npartitions_out=len(self._divisions()) - 1,
            ignore_index=True,
            method=self.shuffle_method,
            options=self.options,
        )
        shuffled = Projection(
            shuffled, [c for c in assigned.columns if c != "_partitions"]
        )

        if isinstance(self._other, Expr):
            drop, set_name = True, "_index"
        else:
            drop, set_name = self.drop, self.other._meta.name
        lru_key = (
            self.other._name,
            self._npartitions_input,
            self.ascending,
            128e6,
            self.upsample,
        )
        computed_divisions = divisions_lru.get(lru_key)
        index_set = _SetIndexPost(
            shuffled,
            self.other._meta.name,
            drop,
            set_name,
            self.frame._meta.columns.dtype,
            computed_divisions,
            self.user_divisions,
        )
        return SortIndexBlockwise(index_set)


class _SetPartitionsPreSetIndex(Blockwise):