Pipelines¶

Pipelines are data science programs designed to solve a specific task. They act as the entry point to start execution. Pipelines are not meant to be reusable, instead extract reusable code into a segment.

Syntax¶

Minimal Example¶

Let's look at a minimal example of a pipeline:

pipeline predictSurvival {}

This declaration of a pipeline has the following syntactic elements:

The keyword pipeline.
The name of the pipeline, here predictSurvival. It can be any combination of lower- and uppercase letters, underscores, and numbers, as long as it does not start with a number.
Curly braces that delimit the body of the pipeline. This is the code that is executed when the pipeline is run. In this example, the body is empty, so running this pipeline does nothing.

Name convention

Use lowerCamelCase for the name of the pipeline.

Statements¶

In order to describe what should be done when the pipeline is executed, we need to add statements to its body, as shown in this example:

pipeline whoSurvived {
    val titanic = Table.fromCsvFile("titanic.csv");
    val head = titanic.sliceRows(end = 5);

    // …
}

Note particularly, that all statements must end with a semicolon. More information about statements can be found in the dedicated document.

Running a Pipeline in VS Code¶

Running a pipeline requires a working installation of the Safe-DS Runner. Follow the instructions in the installation guide to install it.

Afterward, you can run a pipeline via a so-called code lens in the editor. It is displayed above the pipeline once the runner is started successfully. Click on the Run <pipeline name> code lens to run the pipeline:

This executes the pipeline completely, including all side effects, like writing to files. Most of the time, you will want to inspect only one value, instead. For this, additional code lenses are shown above assignments, depending on the type of the assigned value. For example, if the assigned value is a table, you can explore it in a separate view by clicking on the Explore <placeholder name> code lens:

More information about code lenses for value inspection can be found in the dedicated document.