21 Overview

Don’t repeat yourself (DRY) is a software development principle aimed at reducing repetition. Formulated by Andy Hunt and Dave Thomas in their book The Pragmatic Programmer, the DRY principle states that “every piece of knowledge must have a single, unambiguous, authoritative representation within a system.” This principle has been widely adopted to imply that you should not duplicate code. Although the principle was meant to be far grander than that, there’s plenty of merit behind this slight misinterpretation.

Removing duplication is an important part of writing efficient code and reducing potential errors. First, reduced duplication of code can improve computing time and reduces the amount of code writing required. Second, less duplication results in less creating and saving of unnecessary objects. Inefficient code invariably creates copies of objects you have little interest in other than to feed into some future line of code; this wrecks havoc on properly managing your objects as it basically results in a global environment charlie foxtrot! Less duplication also results in less editing. When changes to code are required, duplicated code becomes tedious to edit and invariably mistakes or fat-fingering occur in the cut-and-paste editing process which just lengthens the editing that much more.

Thus, minimizing duplication by writing efficient code is important to becoming a data analyst and in this module you learn to improve your code efficiency with control flow, iteration, and functions.

21.1 Learning objectives

By the end of this module you should be able to:

  • Use a variety of control statements to control the flow of code evaluation.
  • Simplify repetitive code with R’s looping statements.
  • Understand when and how to write functions.

21.2 Estimated time requirement

The estimated time to go through the module lessons is about:

  • Reading only: 3 hours
  • Reading + videos: 5 hours

21.3 Tasks

  • Work through the 3 module lessons.
  • Upon finishing each lesson take the associated lesson quizzes on Canvas. Be sure to complete the lesson quiz no later than the due date listed on Canvas.
  • Check Canvas for this week’s lab, lab quiz due date, and any additional content (i.e. in-class material)