How to best structure csv data for tableau that has "multiple categories"? - tableau-api

Question

I have a set of 100 “student records”, I want to have checkboxes for each "favorite_food_type" and "favorite_food", whichever is checked would filter a "bar graph" that counts number of reports that contain that specific "favorite_food"type" and "favorite_food" schema could be:
name
favorite_food_type (e.g. vegetable)
favorite_food (e.g. banana)
I would like to in the dashboard be able to select via checkboxes, “Give me all the COUNT OF DISTINCT students with favorite_food of banana, apple, pear“ and filter graphs for all records. My issue is for a single student record, maybe one student likes both banana and apple. How do I best capture that? Should I have:
CASE A: Duplicate Records (this captures the two different “favorite_food”, but now I have to figure out how many students there are (which is one student)
NAME, FAVORITE_FOOD_TYPE,FRUIT
Charlie, Fruit, Apple
Charlie, Fruit, Pear
CASE B: Single Records (this captures the two different “favorite_food”, but is there a way to pick out from delimiters?)
NAME, FAVORITE_FOOD_TYPE,FRUITS
Charlie, Fruit, Apple#Pear
CASE C: Column for Each Fruit (this captures one record per student, but need a loooot of columns for each fruit, many would be false)
NAME, FAVORITE_FOOD_TYPE, APPLE, BANANA, PINEAPPLE, PEAR
Charlie, Fruit, TRUE, FALSE, TRUE, FALSE
I want to do this as easy as possible.

Answer 1

Avoid Case B if at all possible. Repeating information is almost always best handled by repeating rows -- not by cramming multiple values into a single table cell, nor by creating multiple columns such as Favorite_1 and Favorite_2
If you are provided data with multiple values in a field, Tableau does have functions and data connection features that can be used to split a single field into its constituent parts to form multiple fields. That works well with fixed number of different kinds of information -- say splitting a City, State field into separate fields for City and State.
Avoid Case C if at all possible. That cross tab structure makes it hard to analyze the data and make useful visualizations. Each value is treated as a separated field.
If you are provided data in crosstab format, Tableau allows you to pivot the data in the data connection pane to reshape into a form with fewer columns and many rows.
Case A is usually the best approach. You can simplify it further by factoring out repeating information into separated tables -- a process known as normalization. Then you can use a join to recombine the tables and see the repeating information when desired.
A normalized approach to your example would have two tables (or tabs in excel). The first table would have exactly one row per student with 2 columns: name and favorite_food_type. The second table would have a row per student/favorite food combination, with 2 columns: name and favorite_food. Now each student can have as many favorite foods as you like or none at all. Since both columns have a name field, that would be the key used to join (combine) the tables when needed.
Given that table design, you could have 2 data sources in Tableau. The first one just pointed to the student table and could be used to create visualizations that only involved students and favorite_food_types. The second data source would use a (left) join to read from both tables and could be used to look at favorite foods. When working with the second data source, you would have to be careful about reporting information about student names and favorite food types to account for the duplicate information. So use the first data source when possible. Finally, you could put both kinds of visualizations on a dashboard and use filter and highlight actions to make interaction seamless despite the two sources -- getting the best of both worlds.