Proportional brushing is a set action technique that allows you to interact with your data by viewing the proportion of your selection against other items without needing to filter from a selection.
In order to better understand this technique, I will build a proportional brushing dashboard and walk you through each step.
For this demonstration I will use the Car Sales Mock Data, which you can find it here.
I upload the data set into Tableau and create a new sheet. For this example we will look at the Car Make (Make) and Sales Price. For a start, drag "Make" into Rows and "Sale Price" into Columns.
![](https://www.thedataschool.co.uk/content/images/2021/12/image-134.png)
Next, we want to see how many cars are a particular color. This is where the proportional brushing technique comes in handy; We create a Color Set from the Color Dimension and choose any item from the list:
![](https://www.thedataschool.co.uk/content/images/2021/12/image-135.png)
We drag the Color Set that we've just created into the Color mark and it should return a similar result as the one below.
![](https://www.thedataschool.co.uk/content/images/2021/12/image-137.png)
However, the viz chart will show you the proportion of (in this example) Aquamarine cars in the selection. In order to change between colors, we will add a new sheet that will only look at the Colors dimension.
![](https://www.thedataschool.co.uk/content/images/2021/12/image-139.png)
We add the Color into Rows and Text Label and untick the "Show Header" option. We're left with the view below that will serve as a dynamic filter for our previous chart.
![](https://www.thedataschool.co.uk/content/images/2021/12/image-140.png)
Next, we add the two sheets we created to a dashboard:
![](https://www.thedataschool.co.uk/content/images/2021/12/image-145.png)
In order to filter the chart on the right using the colors on the left, we will have to add a dashboard action that would change the set values:
![](https://www.thedataschool.co.uk/content/images/2021/12/image-146.png)
We create Change Color Set action using the "Color" Source Sheet with the "Color Set" Target Set.
![](https://www.thedataschool.co.uk/content/images/2021/12/image-147.png)
Finally we update the functionality of the action by assigning the values to set and removing all values from set once the selection is cleared.
![](https://www.thedataschool.co.uk/content/images/2021/12/image-144.png)
As a result, by changing the color field on the left, the chart on the right will update accordingly.
![](https://www.thedataschool.co.uk/content/images/2021/12/image-148.png)
This is how you build a proportional brushing dashboard. Hope you find this helpful!