Taming Data with Tableau Prep

We considered some options for structuring data in Tableau Desktop in the previous chapter. Many of the concepts around well-structured data will apply here as we now turn our attention to another product from Tableau: Tableau Prep. Tableau Prep extends the Tableau platform with robust options for cleaning and structuring data for analysis in Tableau. In the same way that Tableau Desktop provides a hands-on, visual experience for visualizing and analyzing data, Tableau Prep provides a hands-on, visual experience for cleaning and shaping data.

In this chapter, we’ll use the term Tableau Prep broadly to speak of the entire platform that Tableau has developed for data prep and sometimes as shorthand for Tableau Prep Builder, the client application that’s used to connect to data, create data flows, and define output. Where needed for clarity, we’ll use these specific names:

• Tableau Prep Builder: The client application that...

Getting ready to explore Tableau Prep Builder

Tableau Prep Builder is available for Windows and Mac. If you do not currently have Tableau Prep Builder installed on your machine, please take a moment to download the application from https://www.tableau.com/products/prep/download. Licenses for Tableau Prep Builder are included with Tableau Creator licensing. If you do not currently have a license, you may trial the application for 14 days. Please speak with your Tableau representative to confirm licensing and trial periods.

The examples in this chapter use files located in the \Learning Tableau\Chapter 16 directory. Specific instructions will guide you on when and how to use the various files.

Once you’ve downloaded and installed Tableau Prep Builder, you will be able to launch the application. Once you do, you’ll find a welcome screen that we’ll explain when we cover the interface in the next section.

Understanding the Tableau Prep Builder interface

You’ll find a lot of similarities in the interfaces of Tableau Prep Builder and Tableau Desktop. The home screen of Tableau Prep Builder will look similar to this:

Figure 16.1: The Tableau Prep Builder welcome screen with numbering to identify key components of the UI

The following components have been numbered in Figure 16.1:

1. The menu includes options for opening files, editing and running flows, signing into Tableau Server, and various Help functions.

   We’ll define a flow in the next section. For now, think of a flow in terms of Tableau Prep’s equivalent of a Tableau Desktop workbook.

   Also notice the Connections pane to the left, immediately beneath the File menu. It is collapsed initially, but will contain a list of data connections as you create them.

2. The two large buttons at the top give you the option to Open a Flow, which opens an existing Tableau...

Flowing with the fundamental paradigm

The overall paradigm of Tableau Prep is a hands-on, visual experience of discovering, cleaning, and shaping data through a flow. A flow (sometimes also called a data flow) is a logical series of steps and changes that are applied to data from input(s) to output(s).

Here is an example of what a flow looks like in the flow pane of Tableau Prep:

Figure 16.3: An example flow in Tableau Prep

Each of the individual components of the flow are called steps, which are connected by lines that indicate the logical flow of data from left to right. The lines are sometimes called connectors or branches of the flow. Notice that the Aggregate Step here has one line coming in from the left and three branches extending to the right. Any step can have multiple output branches that represent logical copies of the data at that point in the flow.

One important thing to notice is that four of the step types represent the four major transformations...

Using parameters in Tableau Prep Builder

We’ve seen parameters in Tableau Desktop. Parameters in Tableau Prep are very similar and are capable of being used to control the input, output, and logic within a flow.

Let’s say for example that you wanted to create a parameter that indicated whether the dataset was test or production data. Depending on the value, you might change aspects of the data in the flow or even output to a different location.

To create or manage parameters in Tableau Prep Builder, use the Parameters button on the toolbar:

Figure 16.49: Clicking the Parameters button on the toolbar reveals the option to create a parameter or manage any existing parameters

Once you have clicked Create Parameter, you will see another window with all the options for your new parameter:

Figure 16.50: Creating a new parameter

You’ll find much is very similar to creating a parameter in Tableau Desktop. You can give the parameter a...

Options for automating flows

Tableau Prep Builder allows you to design and run flows using the application. Sometimes, data cleansing and prepping will be a one-time operation to support an ad hoc analysis. However, you will often want to run a flow subsequently to capture new or changed data and to cleanse and shape it according to the same pattern. In these cases, you’ll want to consider some options for automating the flow:

• Tableau Prep Builder may be run via a command line. You may supply JSON files to define credentials for input or output data connections. This enables you to use scripting and scheduling utilities to run the flow without manually opening and running the Tableau Prep interface. Details on this option are available from Tableau Help: https://help.tableau.com/current/prep/en-us/prep_save_share.htm#refresh-output-files-from-the-command-line.
• Tableau Prep Conductor, an add-on to Tableau Server, gives you the ability to publish entire flows...

Summary

Tableau Prep’s innovative paradigm of hands-on data cleansing and shaping with instant feedback greatly extends the Tableau platform and gives you incredible control over your data. In this chapter, we considered the overall interface and how it allows you to iteratively and rapidly build out a logical flow to clean and shape data for the desired analysis or visualization.

Through a detailed, yet practical, example that was woven throughout this chapter, we explored every major transformation in Tableau Prep, from inputs to unions, joins, aggregates, and pivots, to outputs. Along the way, we also examined other transformations and capabilities, including calculations, splits, merges, and the grouping of values. This gives you a foundation for molding and shaping data in any way you need.

In the next chapter, we’ll conclude with some final thoughts on how you can use Tableau’s platform to share your analysis and data stories!

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