Creating a Multi-Level Dendrogram Charts in Tableau

Since I released my Dendrogram tutorial I have been inundated with requests on how to a multi-level version. So, in this tutorial, we are going to leverage some interesting techniques to get this effect. I hope you enjoy.

Note: This is an alternative type of data visualisation, and sometimes pushed for by clients. Please always look at best practices for data visualisations before deploying this into production.

Data

Load the following data into the Tableau Public / Tableau Desktop

Dimension,Level,Parent,Value
North America,1,,312
South America,1,,217
Europe,1,,290
Asia,1,,70
Africa,1,,194
Mexico,2,North America,95
United States,2,North America,80
Canada,2,North America,77
Panama,2,North America,60
Brazil,2,South America,45
Chile,2,South America,40
Argentina,2,South America,35
Colombia,2,South America,47
Peru,2,South America,20
Venezuela,2,South America,30
Germany,2,Europe,80
United Kingdom,2,Europe,60
France,2,Europe,55
Italy,2,Europe,50
Netherlands,2,Europe,45
China,2,Asia,10
India,2,Asia,15
Japan,2,Asia,20
South Korea,2,Asia,25
South Africa,2,Africa,34
Nigeria,2,Africa,36
Kenya,2,Africa,40
Ghana,2,Africa,30
Tunisia,2,Africa,25
Senegal,2,Africa,29

Once your data is loaded into Tableau, right-click on the data source and click on Edit Data Source… with the Data Source Editor open, paste the following:

Path
1
100

Note: If you are using Tableau 2020.2 or great i.e. have access to new Relationship Model, you will need to double-click on the originally pasted data source to open up before pasting in the Path Data.

You should get an error as there is no joining column, however, click on Add new join clause, go to Create Join Calculation, type 1 and click OK. Do this for the right-hand side as well. Ensure that you have Inner join selected and you should see the following:

Note: we will be performing data densification to be able to draw our curves

Calculated Fields

With our data set loaded into Tableau, we are going to create the following Calculated Fields:

@Continent Parameter

• Set Name as @Continent
• Set Data type as String
• Set Allowable values as List and add the following values
  • Africa
  • Asia
  • Europe
  • North America
  • South America
• Set Current value to South America

@Region Y Position Parameter

• Set Name as @Region Y Position
• Set Data type to Float
• Set Current value to 0

Path (bin)

• Right-click on Path, go to Create and select Bins…
• In the Edit Bins dialogue window:
  • Set New field name to Path (bin)
  • Set Size of bins to 1
  • Click Ok

Filter

IF [Level] = 1 OR ([Level] = 2 AND [@Continent] = [Parent]) THEN
    TRUE
ELSE
    FALSE
END

TC_Level

WINDOW_MAX(MAX([Level]))

TC_Value

WINDOW_SUM(SUM([Value]))/2

TC_Rank

RANK_UNIQUE([TC_Value],"asc")

X

((INDEX()-1)*0.12)-6

Columns

[X]+(([TC_Level])*18)-12

TC_Sigmoid

1/(1+EXP(-[X]))

Y

([TC_Sigmoid]*([TC_Rank]-(WINDOW_MAX([TC_Rank])+1)/2)/100)
+IIF([TC_Level] = 2, [@Region Y Position], 0)

TC_Max Y

IF [Y] > 0 THEN
    WINDOW_MAX([Y])
ELSE    
    WINDOW_MIN([Y])
END

Zero

0

With this done, let us start creating our data visualisation.

Worksheet

We will now build our worksheet:

• Change the Mark Type to Line
• Drag Filter onto the Filter Shelf and select True
• Drag Level onto the Color Mark
• Drag Dimension onto the Detail Mark
• Drag Path (bin) onto the Columns Shelf
  • Right-click on this pill and ensure that Show Missing Values is selected
  • Drag this pill onto the Path Mark
• Drag Columns onto the Columns Shelf
  • Right-click on this pill, go to Compute Using and select Path (bin)
• Drag Y onto the Rows Shelf
  • Right-click on this pill, go to Compute Using and select Path (bin)

If all goes well, you should see the following:

We will now adjust the Table Calculations to get our Dendrogram:

• Right-click on the Y-pill and go to Edit Table Calculations
  • In Nested Calculations select Y
    • Set Compute Using to Specific Dimensions
    • Ensure that Path (bin) and Dimension is selected and ensure that Path (bin) is on top
  • In Nested Calculations select TC_Rank
    • Set Compute Using to Specific Dimensions
    • Ensure that only Dimensions is selected

Simple huh, but if all goes well, you should now see the following:

Now, we will add our text labels:

• Drag Dimension onto the Label Mark
• Drag TC_Value onto the Label Mark
  • Right-click on this pill, go to Compute Using and select Path (bin)

You should now see the following:

Now, to add our interactivity, we will now add two Parameter actions and a Highlight action.

• Drag Zero onto the Detail Mark
  • Right-click on this pill and convert it to a Discrete Dimension
• Go to the Worksheet Menu and select Actions…
  • Click on Add Actions and select Change Parameter…
    • Set Run action on as Select
    • Set Target Parameter as @Continent
    • Set Field as Dimension with the Aggregation as None
    • Click Ok
  • Click on Add Actions and select Change Parameter…
    • Set Run action on as Select
    • Set Target Parameter as @Region Y Position
    • Set Field as Y with the Aggregation as None
    • Click Ok
  • Click on Add Action and select Highlight…
    • Set Run action on as Select
    • In Target Highlighting select Selected Fields and check Zero
    • Click Ok

You should now have the interactive two level Dendrogram:

Lastly, we will adjust the formatting:

• Double click on the Columns Header and Fix the range to be from -1 to 36
• Hide the Columns Header
• Hide the Y Header
• Hide the Gridlines
• Hide the Zero Lines
• Format the Label

You will want to end up with something like the following:

and boom, we are done! I hope you enjoyed creating this data visualization and learned some cool techniques as well. As always, you can find this data visualisation on Tableau Public at https://public.tableau.com/profile/toan.hoang#!/vizhome/Multi-LevelDendragram/Multi-LevelDendrogram

Summary

I hope you all enjoyed this article as much as I enjoyed writing it and as always do share the love. Do let me know if you experienced any issues recreating this Visualization, and as always, please leave a comment below or reach out to me on Twitter @Tableau_Magic. Do also remember to tag me in your work if you use this tutorial.

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