Method _task

dask/_expr.py:225–256

The task for the i'th partition Parameters ---------- index: The index of the partition of this dataframe Examples -------- >>> class Add(Expr): ... def _task(self, i): ... return Task( ... s

(self, key: Key, index: int)

        return [operand for operand in self.operands if isinstance(operand, Expr)]

    def _task(self, key: Key, index: int) -> Task:
        """The task for the i'th partition

        Parameters
        ----------
        index:
            The index of the partition of this dataframe

        Examples
        --------
        >>> class Add(Expr):
        ...     def _task(self, i):
        ...         return Task(
        ...            self.__dask_keys__()[i],
        ...            operator.add,
        ...            TaskRef((self.left._name, i)),
        ...            TaskRef((self.right._name, i))
        ...        )

        Returns
        -------
        task:
            The Dask task to compute this partition

        See Also
        --------
        Expr._layer
        """
        raise NotImplementedError(
            "Expressions should define either _layer (full dictionary) or _task"
            f" (single task).  This expression {type(self)} defines neither"
        )

    def _layer(self) -> dict:
        """The graph layer added by this expression.