15 The Pipeline Operator: `%>>%`

It is possible to create intricate Graphs with edges going all over the place (as long as no loops are introduced). Irrespective, there is usually a clear direction of flow between “layers” in the Graph. It is therefore convenient to build up a Graph from layers.

This can be done using the %>>% (“double-arrow”) operator. It takes either a PipeOp or a Graph on each of its sides and connects all of the outputs of its left-hand side to one of the inputs each of its right-hand side. The number of inputs therefore must match the number of outputs.

library("magrittr")

gr = po("scale") %>>% po("pca")
gr$plot(html = FALSE)

# The Pipeline Operator: `%>>%` {#pipe-operator}

```{r 05-pipelines-pipe-operator-001, include = F}
library(mlr3)
library(mlr3book)
library(mlr3pipelines)
```

It is possible to create intricate `Graphs` with edges going all over the place (as long as no loops are introduced).
Irrespective, there is usually a clear direction of flow between "layers" in the `r ref("Graph")`.
It is therefore convenient to build up a `r ref("Graph")` from layers.

This can be done using the **`%>>%`** ("double-arrow") operator.
It takes either a `r ref("PipeOp")` or a `r ref("Graph")` on each of its sides and connects all of the outputs of its left-hand side to one of the inputs each of its right-hand side.
The number of inputs therefore must match the number of outputs.

```{r 05-pipelines-pipe-operator-002, fig.align = "center"}
library("magrittr")

gr = po("scale") %>>% po("pca")
gr$plot(html = FALSE)
```