Recap of the preprocessing steps

Unlike the previous chapters, in this chapter, we will only be reinforcing the skills that were taught in the previous chapters. This will be in the form of various exercises and an activity.

This section will help you recap some of the important preprocessing steps covered in this book so far and also go through some techniques that will be used in the exercises:

1. Reading CSV files

   pd.read_csv('file path' , delimiter=';')

As you may recall, the pd.read_csv function is used to read the data from a CSV file available at the specified path.

2. Recasting data

One of the most frequent transformation steps is changing the format from wide format to long format. For example, the following figure shows some data in wide format. You can see that the data for each month is spread across the columns:

Figure 14.1 – Wide format data

Often, when we have to preprocess data, we need data...