Tableau Prep: Up & Running

Chapter 28. Using Data Roles

As you saw in Chapter 26, Tableau Prep’s Group and Replace functionality is pretty incredible with the rich, easy-to-use options that are built into the tool (Figure 28-1).

Figure 28-1. Using Group and Replace in Prep to clean string data

Note

If you haven’t had a chance to explore these, I recommend both revisiting Chapter 26 and attempting Preppin’ Data 2019: Week 2, where you get to use these techniques on the City field. Do this before continuing to read this chapter if you want to avoid challenge spoilers!

The Tableau developers have added an extra level of validation to data cleaning with data roles.

For string data fields, you can now set a specific data role for Prep to test the data against. You can test geographic roles, email addresses, and URLs against Tableau’s own list to see if they are valid.

How to Use Data Roles

When you click on the Data Type icon to change the data type, you will see a drop-down list of options (Figure 28-2). In this example, I’m assigning the City role.

Figure 28-2. Setting a data role in Prep, in this case assigning the City role

By selecting City to compare the list of city names from the Week 2 exercise, you can see what Prep recognizes as a true city name and what it doesn’t (Figure 28-3).

With this highlighting, ...