Build a Marginal Histogram with Map Layers in One Sheet

Most Tableau analysts have never heard of a marginal histogram — and even fewer know how to build one. In this video, I'll show you how to create this advanced visualization from scratch on a single sheet using Tableau's map layers feature.

This technique uses the "Flat Earth" concept to treat your entire canvas as a coordinate system, letting you draw fully custom polygon shapes — no extensions, no workarounds. We'll build a heatmap with bar charts on two axes simultaneously, all driven by calculated fields and LOD expressions.

We're using Trump's Truth Social posting data as the dataset, but the technique works with any time-based data you want to analyze by day and hour.

What you'll learn:

- How Tableau's map layers work and why they unlock charts that don't exist natively

- The Flat Earth coordinate system — how to turn any data into drawable polygons

- Building rectangle polygons using 5-point path calculations

- Creating marginal bar charts (vertical + horizontal) on the same sheet

- LOD expressions to normalize bar lengths across dimensions

- Cleaning up the view: hiding headers, labels, and axes for a polished final result

Download the workbook, data and all of the calculations - https://nlt.kit.com/histogram

-----

Want to go from good to elite in Tableau?

Join Next Level Tableau — 3 live classes per week, office hours, and a community of analysts who take their craft seriously. Use code AUSTIN for $50 off your first month.

👉 https://www.nextleveltableau.com/nlt