Jim Dehner 

 Tableau Visionary and Ambassador

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Do you use parameters – I love them and use them a lot – Let's look at them in more detail

 

Parameters are one-way users can directly input a value into Tableau.  

They are:

  • Single valued –  have one value at a time 
  • Static the value is constant until manually changed by the user 
  • Global – they are available for use throughout the workbook. 

But they don’t do anything until they are used in a calculation, a set, or a filter.  

The same parameter can be used in any mix of calculations or filters on a single or any combination of worksheets or dashboards.  Changing the value of the parameter will change the calculation or filter wherever it is used.  The change takes place as the sheet is opened.

 
 

There are 3 steps to follow when using parameter

  • Create it
  • Put it in the viz
  • Use it in a calculation or filter

 

1-Create it

 

Parameters can be created directly from the data
 
 
 
 
 
Or from the Filter or Set Top N  tabs
 
 
 
 
 
 
 
 

Select Create Parameter – when the window opens  set up the parameter

  • Add a meaningful name that tells the user what to do
  • Select a data type that matches that of the dimension you will use
  • Load values into the parameter either typing directly or from the dimension
  • Click OK and you are done
 
 

 

2 Add the parameter to the viz


All you need to do is open the parameter pill and select Show Parameter Control

 

 

3-Use it in a calculation or a filter


After creating the parameter you need to use it – it is the calculation or the filter that affects the data in the viz – not the parameter by itself. 

Example 1 – Parameter driven T/F filter


The easiest way to use the parameter is in a True/False filter – the expression just says when the subcategory is equal to the one the user selected using the parameter return a True

 

 
 
Placed on the filter shelf and set to True will return this
 
 
 
 

Example 2 – Use it in a Set

 
The same parameter can be used to create a set – The Formula area on the Condition tab acts like a LOD -aggregate the dimension using Max or Min (sorry no Attr()) – set the Max subcategory to the parameter value to select the "In" value – all others are in the "Out"
 
 
 
a possible viz could compare the selected subcategory to all others
 
 
 
 
 

Example 3 – Change all views in a dashboard

 
Parameters are global – when the value is changed it changes all the calculations or filters where the parameter is used –
 
Bring the 2 worksheets together on a dashboard and changing the parameter value will affect both sheets without using filters or actions
 
 

 

Example 4 Top N filtering

 
Parameters can also take on numeric values like in the following Top N example 
 
Create a filter on Subcategory and open the Top tab 
Select Create From Parameter
 
 
 
 

When the window opens – select a starting value and a range

 
 
 
and create a viz 
 
 
 

The user can set the N from the control on the left – Note also the subcategory dropdown will list all subcategories and has a reference to the Top N filter application 

 

Example 5 – Parameter Actions

 

With the 2019.2 release Parameter Actions were introduced given the user an easy visual way to change parameter values for the viz without opening a dropdown – 

I will replace the parameter drop down from the earlier example with a value picker – a simple worksheet with the values (here subcategory names and a circle mark)   A horizontal will work well the overall layout of the dashboard

 
 
 
Add the value picker to the dashboard and create a Parameter Action –
 
 
  • From the Dashboard on the upper ribbon select Action
  • Then Add – Change Parameter
  • Give the action a name
  • The source is – Value Picker 
  • The target is  'Select Subcategory' parameter
 
I used Hover for the example you can select what works best in your analysis
 
 
 
 
 
 
The value of the parameter and the viz will change as the user  hovers order the Value Picker marks – see the video
 
 
 
 
Have some fun with Parameter Actions -They are a major enhancement  for the user experience
 
Example 6 Dynamic Parameters
 
Now the game-changer – Dynamic Parameters – introduced with the 2020.1 release the parameter value list can be updated when the data source is updated and the workbook is opened – see how they work in the simple example below
 
In this example sales data is updated weekly – the initial load includes 4 dates 4/13-18 – the user wants to use a parameter to filter by individual date  – the viz looks something like this:
 
 
 
 
 
 

The dynamic parameter setup adds only a couple of fields to the one you have used so far

  • the parameter that is to be updated and the field in the data set
  • initial value of the parameter (default is Current) 

In the example I added a LOD for the fixed max date in the data set – the parameter value will update to the latest date in the data set

 
 
 
 
When you update the data and when you reopen the book the parameter updates
 
 
 
 
NOTE – UPDATE     the 2020.3 release now will update the parameter and from a data source refresh or edit  – If you are on an earlier version see below
 
 
 
I hope this helps you understand parameters, parameter actions, and dynamic parameters better  – I love using them – with a little practice you can too
 
The workbook examples used in the first part of this post can be found on my Tableau Public site at  https://public.tableau.com/profile/jim.dehner#!/vizhome/parameterworkbook/ValuePickerdrivendb?publish=yes
 
Enjoy
 
Jim
 
 
 
 



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