Step 4: Displaying the pipeline visually

Note

Remember to look at the example code:

Printing out a flowchart of our pipeline

It is all very well being able to trace the data flow through the pipeline. Sometimes, however, we need a bit of eye-candy.

../../_images/simple_tutorial_step4.png
We can see this flowchart of our fledgling pipeline by executing:
pipeline_printout_graph (   'flowchart.svg',
                            'svg',
                            [second_task],
                            no_key_legend = False)

Flowcharts can be printed in a large number of formats including jpg, svg, png and pdf provided that the dot programme from Graphviz is installed.

For this simple case, we have ommitted the legend key which distinguishes between the different states of the various tasks. (See below for the legend key.)

Horribly complicated pipelines!

Flowcharts are especially useful if you have really complicated pipelines, such as

../../_images/simple_tutorial_complex_flowchart1.png

Circular dependency errors in pipelines!

Especially, if the pipeline is not set up properly, and vicious circular dependencies are present:

../../_images/simple_tutorial_complex_flowchart_error1.png