Controlling Flow

Abstract

As you study the capabilities of programming for GIS, applications to your own work may come to mind. For example, you may need to run a geoprocessing tool on distributed batches of datasets or tweak multiple tables before they can be imported into ArcGIS. Before writing scripts for tasks like these, it’s helpful to outline the main steps without belaboring syntax details, but instead using pseudocode, a generic format for outlining workflow. You also need to be familiar with the building blocks of workflow. How will the code make decisions based on the input? How will it repeat a process for each file? Chapters 9 and 10 describe the Python syntax for ‘branching’ and ‘looping’, but that part will seem easy, compared to the logic involved in designing the workflow. This chapter uses pseudocode examples to introduce ‘branching’ and ‘looping’.