Method _layer

dask/_expr.py:258–292

The graph layer added by this expression. Simple expressions that apply one task per partition can choose to only implement `Expr._task` instead. Examples -------- >>> class Add(Expr): ... def _layer(self): ... return { ..

(self)

        )

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

        Simple expressions that apply one task per partition can choose to only
        implement `Expr._task` instead.

        Examples
        --------
        >>> class Add(Expr):
        ...     def _layer(self):
        ...         return {
        ...            name: Task(
        ...                name,
        ...                operator.add,
        ...                TaskRef((self.left._name, i)),
        ...                TaskRef((self.right._name, i))
        ...            )
        ...            for i, name in enumerate(self.__dask_keys__())
        ...         }

        Returns
        -------
        layer: dict
            The Dask task graph added by this expression

        See Also
        --------
        Expr._task
        Expr.__dask_graph__
        """

        return {
            (self._name, i): self._task((self._name, i), i)
            for i in range(self.npartitions)
        }

    def rewrite(self, kind: str, rewritten):
        """Rewrite an expression