Dataskera

Ridgeline Chart

One density curve per group, overlapping down a shared axis. Where a violin plot compares a handful of distributions side by side, a ridgeline compares many of them down a page: months of response times, cohorts of scores, years of temperature. The overlap is the point, and it is also the trap, so it is a setting.

Data Requirements

Your Tableau worksheet should include:

  • 1 Dimension for the Group encoding. One ridge per value.
  • 1 Measure for the Value encoding. The measure whose distribution you want to see, at row level rather than as a total.

Add Ridgeline Chart to your worksheet

First, download the manifest file. It tells Tableau where to load the extension from.

Download ridgeline.trex

Direct link: https://dataskera.com/downloads/ridgeline.trex

Then, in Tableau:

  1. On the Marks card, open the Mark type dropdown, and under Viz Extensions choose Add Extension.
  2. In the Add an Extension dialog, choose Access Local Viz Extensions, then open the ridgeline.trex file you just downloaded.
  3. When Tableau asks, allow the extension to access the data in the workbook.
  4. The welcome screen appears. Sign in with your Dataskera account, or on Tableau Desktop choose Use on Desktop without an account. See Signing in & access below.
  5. Build the chart: drag a dimension onto Group and the row-level measure onto Value.
Tableau Server or Cloud:
A site admin must allow the extension by adding its URL to the site's safe list, and the view needs the Download Summary Data permission. Extension URL: https://vizextension.dataskera.com/ridgeline/ridgeline.html

Signing in & access

Ridgeline Chart is free. Whether you need to sign in depends only on what you are doing. Viewing a dashboard never asks for an account, and authoring is free too.

Viewing a dashboard
No account

People who only view a dashboard are never asked to sign in and are never blocked.

Editing on Tableau Desktop
Optional

Sign in, or continue without an account in a single click.

Editing on Server or Cloud
Free account

Sign in with your Dataskera account to author on the web.

No account yet? Create one free in under a minute. No credit card required.

Format panel

Open the Format panel from the extension menu to customize the chart. It is for the dashboard author and is not shown to viewers. It has four tabs:

  • Ridges: the overlap, whether each ridge is scaled to its own peak or to one shared scale, and the group order.
  • The Curve: the smoothing multiplier, fill opacity, outline width, and the smallest group a density is drawn for.
  • Marks and Axis: the median mark, baselines under each ridge, the value axis, and the observation count beside each ridge.
  • Color: a palette, a precise colour per category, and the overall opacity.
  • Legend: show or hide it, its position around the chart, an optional show/hide toggle for viewers, the colour swatch, and the content of each entry.
  • Tooltip: show or hide it, its colours, decimals, and a template you write yourself from the placeholders the chart provides.
The same estimator as the Violin Plot:
Silverman's rule of thumb, robust to outliers through the interquartile range and degrading to the standard deviation when that is degenerate. The smoothing setting scales it and never replaces it, so two Dataskera charts of the same data agree with each other.
Height means one thing or the other:
Scaled to its own peak, every ridge fills its row and the heights show shape only. On a shared scale the heights become comparable and a group with few observations looks as flat as it really is. The chart says which of the two you are looking at.
Back to front, always:
A ridge is covered by the one below it and never the other way round, so the reading order is fixed whatever the overlap. Past a heavy overlap the chart says how much the ridges hide of each other.
A density needs observations:
Groups with fewer than your minimum are held back and named rather than drawn as a spike. A density from a handful of points is a shape, not a distribution.