Dataskera

Gantt Chart

One bar per task from a start to an end, so a plan, a schedule or any set of ranges reads as a timeline. It also shows the one thing every project reader looks for and no plain Gantt carries: how far along each task actually is, drawn inside its own bar.

Data Requirements

Your Tableau worksheet should include:

  • 1 Dimension for the Task encoding. One bar per value.
  • 1 Date or Measure for the Start encoding. Where each bar begins.
  • 1 Date or Measure for the End encoding. Where each bar ends.
  • 1 Measure, optional for the Completion encoding. How complete each task is, either 0 to 1 or 0 to 100.

Add Gantt Chart to your worksheet

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

Download gantt.trex

Direct link: https://dataskera.com/downloads/gantt.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 gantt.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 Task and the two ends onto Start and End. Add a completion measure to fill the bars.
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/gantt/gantt.html

Signing in & access

Gantt 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:

  • Completion: fill each bar to its completion, read the scale as 0 to 1 or 0 to 100 or let the chart detect it, print the completion, and mark tasks behind their own elapsed time.
  • Timeline: the sort, bar height and corner radius, gridlines, the line on today, the duration label and its unit, task names, number format and font.
  • 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 scale is decided once, for the whole column:
A completion column arrives as 0 to 1 or as 0 to 100 and nothing in the data says which. Deciding row by row looks clever and is wrong: a fraction column holding a single 1.4 overshoot would have that one row read as 1.4 percent while its neighbours read as fractions. The decision is made once from the column's largest value, the chart says which reading it took, and you can force it.
The shortfall, not a second Today line:
A task less complete than the share of its own schedule already elapsed is shown by shading the gap between where the work has got to and where today falls on that bar. A vertical mark at the elapsed share would sit on the Today line every time, by construction, and say nothing new.
A bar with completion becomes a track:
So the fill carries the colour and reads at any opacity. A task with no completion value is drawn without a fill rather than as zero, and the chart says how many.
Ends that arrive the wrong way round:
A task ending before it starts has its two ends swapped so the bar stays readable, and the chart says it did.