Fun with parameters: An introduction

by Naledi Hollbruegge

One of our tasks for this week is to each prepare a lesson for the group. I was assigned the topic of parameters and for the start of this week wanted to provide a quick introduction to the topic.

Parameters allow you to interject dynamic values to your visual. They are often used as filters but are themselves variables. The difference is that filters trim data, while parameters control the value of a variable. This variable is used in a calculation in order to give more control to the end user. Interactivity can be added through parameters in lots of different ways, for instance:

  • User-controlled thresholds
  • What-if-analysis
  • Dynamic field, axis, titles, etc.
  • Filtering across disparate data sources
  • Top N

Parameters provide a single output to another element so they are only useful once that value is tied to something else. There are four basic steps to creating a parameter:

  1. Create the parameter
  2. Create the calculation using the parameter
  3. Use the calculated value in the view
  4. Show the parameter so the user can interact with it

Parameters are best understood by working through some examples, so over the next few days I will cover some of the applications that I have so far found most useful.