Combine your data with Union in Tableau 9.3

Update: Tableau 9.3 is here! Download now to try out the feature outlined below. 

Data doesn’t always come ready for analysis. As many of you have experienced, some data needs a lot of work before it can be sanely analyzed.

The good news: Tableau 9.3 offers a quick fix to that problem. We’ve added Union, which helps you piece together data that’s been split into little files. Let me show you how it works with some of New York City’s bikeshare data.

When I went to the NYC portal to get the data, I was surprised to find that it had been split across multiple csv files.

Before Tableau 9.3, I would’ve had to copy and paste all of the data into a single file to do my analysis. But now I can just drag and drop the tables into the canvas to create my Union.

You can customize your Union from the table right-click menu and see the Union dialog. Here you can add more tables, remove tables, and rename your Union.

Once I’ve included all the right tables in my Union, I can check the output in the data grid. I have a problem, though: There are a ton of nulls in my data source! Here’s the view after I sort the fields alphabetically:

Turns out the NYC government renamed the fields in each file. “Bike#” was renamed to be “Bike Key.” And “Duration” became “Duration (sec),” then “Duration(Sec).” This is a pretty common problem when data is split across multiple files, which is why Tableau 9.3 lets you quickly merge columns. Just select the columns you want, right-click, and merge!

With just a few clicks, I can quickly merge and name my fields.

And now my data is ready for analysis!

For those of you who asked for a “filename” column in the Tableau 9.2 beta, you may have noticed a new column, “Table Name.” This column contains the name of the file from which each row originated. If you have dates or other information encoded in the file name, this column gives you access to it.

Tableau 9.3 is currently in beta. Sign up for our beta program, which is open to all Tableau customers.

Subscribe to our blog