I just finished week 2 of the Preppin Data challenge and wanted to walk through my approach. One of the things I love about Tableau and Tableau Prep is that there are a number of different ways to get at the same result.
This week Carl & Jonathan gave us a file that had a big header, names that needed to be cleaned, and metrics that needed to be moved to columns. The output needed to be 6 columns and 14 rows.
After setting my connection to the file the first thing I did was check the Use Data Interpreter box. This helper removed the unnecessary header at the top of the file.
Whenever I built something in Tableau Prep I like to always add a clean step after my connection to get a sense of what is in the data. When I did this I noticed that my city field had a value called “city”. I knew from looking at the initial file that this was a secondary header so I right clicked on the value of city and selected exclude.
At this point I also added an aggregate to see how many rows were in my data set. I like to add these as I build out a flow to get a sense of how my record counts change as I build out different steps.
I added another clean step and I did this because I like to partition out my changes when I build something new (I’m quirky). I could have done these all in the first step. In this step I grouped the various city names by pronunciation This took care of all but two values. I edited the group and manually added “nodonL” to London and “3d!nburgh” to Edinburgh. In this step I also created the new header field which combined the metric and the measure and then removed those fields as they were no longer needed.
The next step was to move the values from the rows to columns. This is done in a pivot step. Most of the people I help with Prep think Pivot = Pivot table and are confused when they add that step. Pivot will reshape your data. My pivoted field is my new field that I created in the prior step and my field to aggregate is the value field.
At this point I also added an aggregate step to make sure I had 14 rows as the instructions called for. This is the full view of my flow.
Thanks for reading and happy preppin!