Understanding and Creating a Radar Chart in Tableau: A Comprehensive Guide - Part II

How to Create a Radar Chart Ring Background in Tableau

In the previous blog on Radar Charts, how to create a radar plots in Tableau was covered. If you missed it, make sure to check it out for building radar charts step by step. In this blog, creating a ring background for a radar chart and incorporating into the radar plot is covered, which helps in enhancing the visualization.

Steps to Create the Ring Background for a Radar Chart

Step 1: Create an Excel Sheet

You need to prepare your data in Excel to serve as the foundation for the radar chart background. Follow these sub-steps:

1. Create a "Month" Column

   • Add the names of the months (or any other dimension you want to display as labels) .

     
     

2. Create a "Ring" Column

   • Define the number of rings you want. For instance, if you need 5 rings, create values like Ring1, Ring2, Ring3, Ring4, and Ring5.

     
     

3. Set Ring Values for Your Metric

   • Choose the metric you’re visualizing on the radar chart. For example, if your metric is Sales and the maximum value is 22,000 or 27,000, set ring values incrementally for proper visualization:

     5,000, 10,000, 15,000, 20,000, and 25,000.

     
     

4. Add Columns

   • Sales Column: Enter the values you’ve set for each ring.

   • Radius Column: Use the same values as the Sales column to represent the size of each ring.

     
     

Your Excel data should look something like this:

Month	Ring	Sales	Radius
December	Ring1	5000	5000
December	Ring2	10000	10000
December	Ring3	15000	15000
December	Ring4	20000	20000
December	Ring5	25000	25000
January	Ring1	5000	5000
January	Ring2	10000	10000
January	Ring3	15000	15000
...	...	...	...

Step 2: Import Data into Tableau

• Open Tableau and connect the Excel file as your data source.

• Make sure the data source reflects your table with the Month, Ring, Sales, and Radius columns.

Step 3: Create an Angle Calculation

We need to create a formula that divides the ring into equal segments, such as 12 months. Use the following calculation:

Angle = -RUNNING_SUM(2 * PI() / 12) + PI()/2

• Explanation:

  • 2 * PI() / 12: Divides the circle into 12 equal parts (one for each month).

  • -RUNNING_SUM: Moves values clockwise for proper alignment.

  • +PI()/2: Positions Dec (or your starting segment) at the top-center of the radar chart.

Step 4: Create X and Y Calculations

X-Axis Calculation

X = [Radius] * COS([Angle]

Y-Axis Calculation

Y = [Radius] * SIN([Angle]

These calculations use trigonometry to plot the rings in a circular format.

Step 5: Build the Visualization

1. Change Chart Type to Polygon

   • In the Marks card, set the chart type to Polygon.

     
     

     

     
     

2. Set Details and Path

   • Drag Month (or your dimension for the radar segments) into Detail.

   • Drag Angle into Path and compute it using Month.

     
     

     

     
     

3. Set X and Y Axes

   • Drag the X calculation to the Columns shelf and compute it using Month.

   • Drag the Y calculation to the Rows shelf and compute it using Month.

     
     

     

     
     

     

     
     

     

     
     

4. Add Rings to Color

   • Drag the Ring field to the Color card and reduce opacity / add borders to see all the rings in different shades.

     
     

     

     
     
     
     

     

     
     

     

     
     

5. Adjust Axes

   • Set the X-Axis and Y-Axis to ranges like -25,000 to 25,000 to ensure the entire ring structure is visible and well structured to fit as a background for the radar chart. Then finally hide the headers.

     
     

Step 6: Finalize and Enhance

1. Go to the Dashboard

   • Add labels for your rings, such as Jan, Feb, March ,.. using Objects in the dashboard.

     
     

     

     
     
     
     

2. Save and Export

   • Once complete, you can use this ring background as an image for your radar chart.

     
     

How to Add the Radar Background to Your Radar Chart in Tableau

After creating the radar background rings, you can integrate it into your radar chart visualization as a background image. Here’s how to do it:

Steps to Add Radar Background to Your Radar Chart

1. Go to the Map Menu

   • In Tableau, navigate to the top menu and click on Map.

   • Select Background Images from the dropdown.

   
   

   

   
   

2. Add Your Background Image

   • Click Add Image and browse for the image file containing your radar background rings.

   • Give the image a name (e.g., "radar_ring_background").

   • Adjust the dimensions of the image to align with your chart's axes.

   • Use the X-axis (horizontal) and Y-axis (vertical) ranges that match your radar chart's scale. For instance:

     • X-Axis: -25,000 to 25,000

     • Y-Axis: -25,000 to 25,000

   • click OK.

Fine-tune the X and Y axis ranges in your radar chart to ensure the radar background rings fit snugly behind your data visualization.

This step-by-step guide ensures you have a clean and professional radar chart ring background that complements your data and enhances its visual appeal.

Step	Details
1. Excel	Prepare data with columns: Months, Rings, Sales, and Radius.
2. Calculated Fields	Create calculated fields for plotting the radar background:
- Angle	Angle = -RUNNING_SUM(2 * PI() / 12) + PI()/2 for segment positions.
- X (Coordinate)	X = [Radius] * COS([Angle]) to define horizontal positions.
- Y (Coordinate)	Y = [Radius] * SIN([Angle]) to define vertical positions.
3. Plot the Rings	Use the calculated fields to create a circular polygon for the rings.
4. Save as Image	Export the rings as an image for use in the radar chart.
5. Import into Radar Chart	Add the background image to your radar chart in Tableau.
6. Enhance Visualizations	Adjust colors, labels, and axis ranges for better readability.

Try it out, and you’ll see how it elevates your radar chart visualization! Happy Radaring !!