Creating a Donut Chart - Transcript

s1042 Tableau: Building a Dual-Axis Donut Chart

A donut chart is a sophisticated variation of a pie chart that utilizes a "hole" in the center to display aggregate totals or labels. This guide outlines the technical steps to create this effect using Dual-Axis overlays and Placeholder Fields to achieve a professional, layered visual.

Phase 1: Configuring the Dual-Axis Foundation

If you want to create a donut effect, then you must stack two separate pie charts on top of each other using a dual-axis configuration.

  • Action: Create two placeholder fields on the Columns shelf (e.g., MIN(0) or AVG(0)).

  • Implementation: Right-click the second placeholder and select Dual Axis to synchronize the views.

  • Result: This provides two independent Marks cards, allowing you to control the inner and outer "rings" of the donut separately.

Phase 2: Constructing the Outer Ring

To define the primary data segments, utilize the first Marks card to build the outer ring of the donut.

  • Mark Type: Set the Mark Type to Pie.

  • Color Logic: Drag the dimension you wish to segment (e.g., Region) onto the Color tile.

  • Size & Details: Place your measure (e.g., Sales) on the Angle tile and add percentage of total to the Label tile for clarity.

Phase 3: Creating the Inner "Hole" with LODs

Because the center of the donut should remain clean while displaying high-level aggregates, you should use the second Marks card to create a white "inner pie".

  • Action: Switch to the second Marks card and set the color to white.

  • LOD Calculation: Use a Fixed Level of Detail (LOD) expression to calculate the total sales across the entire data set.

  • Sizing: Adjust the Size slider on this Marks card to be slightly smaller than the outer ring, creating the "donut hole" effect.

  • Center Label: Drag your total sales LOD field onto the Label tile of this second card to display the grand total in the center of the chart.

Phase 4: Formatting and Final Polish

To achieve a professional output, remove technical artifacts and refine the labels.

  • Clean Up: Right-click the view and uncheck Show Header for your placeholder axes to hide the zero lines.

  • Number Formatting: Open the context menu for your labels and format them as percentages with two decimal places for precision.

  • Label Alignment: Use the Label tile settings to ensure the text is centered within both the segments and the center hole.

 

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