At this stage, it is supposed that the reader has already acquired enough technical knowledge to code a full application. This is naturally necessary to produce a successful output, but sometimes it is not enough. There are often thousands of different ways to get similar results in R or any other programming language. However, some of them are usually better than others in different ways: scalability, clearness, performance, timings, and so on.

In this chapter, an application is developed from scratch so that the reader comes face to face with a typical programmer's "real world" challenges where the pros and cons of different approaches are evaluated and decisions are taken with all their implications, that is, taking into account the possible drawbacks of the choices made. In this sense, the most important thing is to be conscious about all the strong points and especially, the weak points of your code.

This chapter will be divided into...