How do I build a Trellis chart in Tableau?
Trellis maps are a great way to help you compare measures in one concise view across multiple evenly spread rows. They are an effective method to add context to a view without making your end user do extra work.
These were one of the many charts we were taught to build during our training program with the Information Lab Ireland. In this blog, I’ll provide a table calculation approach to automatically and quickly generate one, using formulas that were originally created by Chris Love of The Information Lab UK.
Steps to create Trellis Chart:
Let’s start by looking at the Sample-Superstore data where we would like to view which are the top 9 States with the most Sales.
- First, let’s right-click Order Date, before dragging and dropping it as a continuous pill into columns. Then we’ll drag SUM(Sales) into Rows
- Now we’ll have to create a couple of calculations that are going to tell Tableau how to split the view into equal parts of rows and columns. We will use the INDEX() and SIZE() functions to create a dimension for the columns and a dimension for the rows as shown in the formula calculations for the X and Y axis below.
- Now drag and drop the X-Axis (or column divider) into columns and the Y-Axis (or row divider) into rows as well (this still looks a little strange right now but be patient and keep reading!)
- Then drag the State field into the Detail Marks card. But this still doesn’t look right…
- This is because we need to tell Tableau how to calculate these views. In this case, we want to calculate by State. So we’ll click on one of these dividers, then Compute Using and select State. Repeat this step for the other divider.
- We then want to select the top 9 States with the most Sales. For this, we’ll Drag and Drop the State field into Filter. Then right click on State inside Filters and select the Top 9 Order ID (Count Distinct) before choosing OK.
- Then right-click on State again and choose Sort before setting the configuration to sort by the SUM of Sales in descending order.
- And voila! Your very own trellis chart which effectively reveals the stark contrast in sales between the top states as shown by their differing area sizes.
Stay tuned with the our progress with The Graduate Training Programme if you want to learn more neat chart tricks like this!
What is the The Information Lab Ireland’s Graduate Training Program?
The Information Lab Ireland’s Graduate Training Program is a two-and-half-year program for people with drive and a desire to try something new in data.
When they join us, most of our candidates are completely new to Tableau and Alteryx. After a 14-week intensive training course, they become part of our consulting team, available for long-term engagements with our clients.
We train our graduates in both the technical and soft skills required to be a top-class data analytics consultant.
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When we are hiring, we will post any recruiting news and event information on our blog. So keep your eyes out here.
The Information Lab Ireland is at the forefront of creating a data-driven culture in Ireland.
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