What is the best way to plan how to prepare your data in Tableau Prep?
On the second day of training at the data school, we learned the ins and outs of data preparation. Since I had, previously, only had a basic understanding of reshaping data using pivot tables, it was welcoming to get a proper run through why my previous pivot tables never seemed to work out how I imagined. The key take-home messages were that for starters…1) you need to know your data and 2) plan, plan, plan.
Step 1: Sketch Your Original Data
The best way to get to know your data (rather than taking it out for dinner) is to do a basic sketch of your data set. This doesn’t mean you have to sketch EVERYTHING, just the basics to help you understand the layout and identify your categories and measures and which data types you are working with.
Step 2: Your Desired Data State
You can then sketch how you want your data to look. You can think about what the final structure should look like and what each final field of data should contain.
Step 3: Annotation
The third step involves annotating your tables to identify what changes need to be made and in what order to achieve your desired dataset. Does this involve replacing missing values? Splitting combined data fields? Are their row duplicates? I, personally, had difficulty finding which order the changes needed to be made so I started by writing the steps from each dataset and then deciding which order they should be completed. It also helps to sketch how each step should look as a table.
The preparation exercises we were tasked with only involved the planning aspect outside of Tableau Prep software, so I’m keen to learn how to start doing this in Tableau Prep later this week.