Toan Hoang

Drawing Layered Filled Circle Charts

Toan Hoang

I created this bespoke data visualisation I had more time and more actively participating in #MakeoverMonday and for the UNESCO-IHE. I wanted to create a slightly different take on a stacked bar chart, so do have fun with this one.

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 Tableau Desktop / Tableau Public. 

Segment,Value
A,20
B,30
C,40
D,10

Once your data is copied 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
362

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 need two records for each Country as we are going to be drawing lines and using densification to get more points on our canvas. For more information, check out our article on Data Densification.

Calculated Fields

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

Create Path (bin)

Index

(INDEX()-1)

Segment Index

INDEX()

TC_Value

WINDOW_MAX(MAX([Value]))/100*2

TC_Value Label

WINDOW_MAX(MAX([Value]))/100

TC_Starting Point

RUNNING_SUM([TC_Value])-[TC_Value]

X

SIN(RADIANS([Index]))

Y

IF 
    [Index]<180
    AND COS(RADIANS([Index]))+1 >= [TC_Starting Point]
    AND COS(RADIANS([Index]))+1 <= [TC_Starting Point]+[TC_Value] THEN
    COS(RADIANS([Index]))+1
ELSEIF 
    [Index]>=180
    AND COS(RADIANS([Index]))+1 >= [TC_Starting Point]
    AND COS(RADIANS([Index]))+1 < [TC_Starting Point]+[TC_Value] THEN
    COS(RADIANS([Index]))+1
ELSE
    NULL
END

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

Worksheet

We will now build our first worksheet:

If all goes well, you should see the following:

As you can see we are pretty much there, but we do have a small gap between the segments. This gap occurs because we are only using 360 points around a circle, and therefore, there will be a small gap. To solve this, we will need:

You should have now closed the gaps, and have the following:

Now we will adjust the cosmetics:

You should finally have the following:

and boom, we are done, you can find my data visualisation on Tableau Public at https://public.tableau.com/profile/toan.hoang#!/vizhome/LayeredFilledCircleCharts/LayeredFilledCircleChart

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 Visualisation, and as always, please leave a comment below or reach out to me on Twitter @Tableau_Magic.

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