Tableau Prep is a self-service data preparation product that provides a visual, easy means of cleaning, shaping and combining data. It is used in association with Tableau Prep Conductor, which enables analysts and businesses to better monitor, manage and schedule prepped and up-to-data data.

There are several great aspects to Tableau Prep, which include;

  • Versatile Set-Up: Tableau Prep is able to access, clean and combine multiple data sources easily.
  • Visual: It allows users to view row-level data throughout the whole data preparation process and create complex workflows to provide up-to-date data. This makes Tableau Prep a very visually informative and more understandable resource for viewing data.
  • Fast: Tableau Prep can generate instant results, even with large data sources.
  • Flexible: Users can build towards their desired outcomes, observe data change immediately and easily reverse changes, re-edit, update and clean a dataset as needed.
Get Started > Connecting

Connect to your data and create an Input step as your starting point. The Input pane contains configuration options for the data and shows the data types, fields and value examples from a dataset. Additional sources can be added via the Connections pane. It is also possible to combine multiples into one Input step, using the Multiple Files tab in the Input pane.

Once connected, the Tableau Prep Builder workspace opens. The view is divided into two main sections, the main workspace or Flow pane (upper portion) and the Input pane (lower portion).

Before combining files, it can be a good idea to first look over them to see if there are any immediate issues.

The Input step can be used to is to see preview the values, view the data settings and change data types. This step can also select which fields to include or filter from the workflow. Tableau Prep tracks changes in the Changes pane and adds annotations in the Flow pane to help keep track of the actions taken.

Connect to Data
Set your Data Sample Size

Clean Your Data

Next, examine the data. You want to improve on it by applying various cleaning, shaping and combining operations.

Add a Cleaning step after the Input step, and whenever you wish to apply cleaning operations to your fields (e.g.; filtering, splitting, renaming or merging).

Clean and Shape Data in Tableau Prep

Add an Aggregation step to aggregate and group fields and to change the data detail level.

Tableau Prep Example

In the example we worked on, you can see that a flow line connects the steps. Similar to Alteryx, these flow lines can be easily added, moved around and removed.

When you add a cleaning step, the workspace is split into the Flow pane (1), the Profile pane (4) (plus Toolbar (2)) and a Data Grid (5). Also note the Changes column (3) for keeping track of changes.

The Profile pane shows the data structure and summarizing the fields so that you may more easily identify related values, null values and outliers. While the Data Grid shows the row level detail for the fields.

Build and Organize Your Flow

Combining Your Data

When working with multiple datasets, once they are cleaned up the next stage is usually to combine them.

If the files have similar fields after cleaning them up, it may be possible to Union them as follows. In the Flow pane, drag a (cleaned) step from one data file onto another cleaned set and drop this onto the Union option. Tableau automatically matches up the fields that had the same names and types.

Another option if there is at least one filed in common is to Join rather than Union the data (below). When Joining, Tableau Prep will show the results of the join in the Join Profile. The far left pane of the Join profile is where to interact with a join. It is also possible to edit values in the Join Clauses panes directly, or perform cleaning operations in the Join Results pane.

Image Source: https://help.tableau.com/current/prep/en-us/prep_combine.htm

Tableau Prep will default to an Inner Join but this can be changed where required. Add the cleaning step after joining to clean the results. It is also possible to undertake cleaning operations directly in the Join step.

Aggregate, Join, or Union Data

Reviewing Changes – And Don’t Forget to Save as You Go!

To the left of the Profile pane is a column called Changes. Clicking on the arrow to open it will show a list of every change that has been applied to the data so far. It is possible to change their order, edit or delete these changes – which allows for a great deal of potential experimentation!

Don’t forget to periodically SAVE your work. It is possible to save Tableau Prep Flows flow files (.tfl) or as a packaged files (.tflx) which included with local data files to better share files with other.

Saving and Sharing Work

Run Flows for Output

Finally, you want to generate your output file to start analyzing it through Tableau Desktop. Depending on what you have to work with, you can output to a file, published data source or to a database. Once an Output step is added, Tableau Prep offers a view of the final data. Name and select the type of output file wanted and where to save the file.

Add an Output step and run the flow to generate your extract file!

 

Additional Sources:

Tableau Prep Help
Tableau Prep Overview

To Connect/Input
Union Files and Database Tables in the Input Step

To Clean Your Data
Edit Field Values

To Examine The Data
Filter Your Data
Use Data Roles to Validate your Data

To Clean, Filter and Shape Data
Copy Steps, Actions and Fields
Create Level of Detail and Rank Calculations
Pivot Your Data
Use R and Python Scripts in Your Flow

Tamara Allcock
Author: Tamara Allcock

Tamara has an interesting background in veterinary science, data analytics and retail. She discovered her passion for analytics while working on a range of research projects involving Australian and exotic wildlife. She was excited to learn about the Data School and the opportunities it provided to develop this interest into a career path. It may be a common preference, but she thinks you can’t go wrong the variety of options a delicious pizza offers. In her spare time, Tamara is an avid reader and watcher of fantasy, science-fiction or assorted pop culture and also enjoys painting, craft projects and writing.