Toan Hoang

Drawing Curved Bar Charts in Tableau

Toan Hoang

I was having a quiet weekend and thought I would have a little fun with some bar chart variations, as such, I played around with creating Curved Bar Charts in Tableau. This is a bespoke version of a standard Bar Chart, but it does have a cool visual appeal to it, I hope you have fun and enjoy this quick tutorial.

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.

Country,Value
United States,60
United Kingdom,70
India,50
Australia,60
France,30

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
0
200

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, Parameters and Bins:

Create a Distance Parameter

Create Path (bin)

Index

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

Note: this is to implement the Sigmoid Curve function.

TC_Value

WINDOW_MAX(MAX([Value]))

Y

IF [Index] <= 6 THEN
    (1/(1+EXP(-[Index])))
ELSE
    (1/(1+EXP(-(12-[Index]))))
END
* [TC_Value]

TC_Country Rank

RANK_UNIQUE([TC_Value])

X

[Index]+([TC_Country Rank]*[Distance])

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

Worksheet

We will now build our first worksheet:

If all goes well, you should have the following:

So we are almost there, let us adjust the cosmetics:

If all goes well you should end up with the following Curved Bar Chart.

This is normally where I would say boom, I am done, but not quite yet. Upon special request, a friend asked me if I can make these overlapping for a cosmetic effect.

Curved Overlapping Bar Charts

Note: use this version with extreme caution. I would go as far as say use this for fun only.

Create a new Worksheet:

Adjust the cosmetics in the same way as before (and add a little transparency), and if all goes well you should see the following:

Try adjusting the Distance parameter and see what you can come up with. and now, we are done, you can find my data visualisation on Tableau Public at https://public.tableau.com/profile/toan.hoang#!/vizhome/CurvedBarCharts/CurvedBarCharts

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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