Figure 3. Example Snakemake workflow.

( a) workflow definition; hypothesized knowledge requirement for line readability is color-coded on the left next to the line numbers. ( b) directed acyclic graph (DAG) of jobs, representing the automatically derived execution plan from the example workflow; job node colors reflect rule colors in the workflow definition. ( c) content of script plot-hist.py referred from rule plot_histogram. ( d) knowledge requirements for readability by statement category (see subsection 3.2). The example workflow downloads data, plots histograms of city populations within a given list of countries, and converts these from SVG to PDF format. Note that this is solely meant as a short yet comprehensive demonstration of the Snakemake syntax.