In order to understand how Tableau creates graphics and how you can change that to get the look and feel you want, it’s necessary to understand the difference between Tableau Dimension vs Measure, and Discrete vs. Continuous.
Dimension vs Measure in Tableau
Tableau can handle a lot of different data types, from text values to dates and date/times, to numbers, percentages, geographical values like latitude and longitude, and true/false Boolean values.
It’s smart enough to look at your data and automatically classify it into either a Tableau dimension or Tableau measure. Tableau dimensions are typically text fields and dates. These Tableau dimensions are used to create headers or segment data.
Each new header in Tableau creates what’s called a Pane.
Tableau Measures create axes on your graph and are typically numerical. These Tableau measures are dependent on what you use as a Tableau dimension. So we could see the sum of sales (the Tableau measure) by region (the Tableau dimension). We could also see the average discount percentage (the Tableau measure) by a salesperson (the Tableau dimension).
- To see the Tableau dimension and Tableau measure in action, open a new tab.
- Now on your Tableau canvas, drag Product Category to the Rows shelf. You’ll see that Tableau creates three rows, one for each category (Furniture, Office Supplies, and Technology).
- Now, drag Customer Segment to the Columns shelf. You’ll see that Tableau creates four columns (Consumer, Corporate, Home Office, Small Business). You’ve now got a Tableau table with headers where numeric data can be organized.
- Double click Sales and you now have a Tableau table of sales figures by customer segment and category.
- To create an instant visual, rather than double click Sales, drag Sales out onto the view by clicking on it once and dragging it next to Product Category on the Rows shelf. You now have a series of Tableau bar charts with the sum of sales as your y-axis.
- Next to the Customer Segment pill on the Columns shelf, drag out Order Date and place it to the right.
- You’ll see your view in Tableau has changed in two ways: 1) Tableau changed the view from a bar chart to a line chart because you are visualizing trends over time, 2) Tableau maintained the original structure of the table with Department on rows and Segment along the top columns, but Tableau added additional columns for each year and shows the trend by year for each Customer Segment.
- Tableau is almost infinitely customizable and rearranging the order of the pills on your shelves changes your view. Move the Order Date pill before Customer Segment. You’ll see some big changes to the view again.
- You’ll see that you still have Category creating the rows of the table. But now you see Customer Segment as the inner columns of the chart segmented by year. You will also see it’s changed to a Bar chart, as now you are comparing Sales by Customer Segment per year, rather than showing sales trends over time per Segment.
- Note that the innermost fields on the shelves determine the mark type (bar, line, etc.). You can always change those by using the drop-down menu on the Marks card in the middle left pane. Tableau enables you to put up to 16 Tableau dimensions and Tableau measures on the shelves, creating as detailed of a view as you desire.
What if We Wanted to Convert a Measure to a Dimension? How Would the Viz Change?
- Open a new tab and drag Unit Price to Rows. Because it’s classified as a Tableau Measure, you’ll see it creates an axis of sum of the price and shows us a bar.
- Drag out Product Category to Columns. We now have a bar chart of the total price per department.
3. But what if we wanted to see prices as discrete values? In other words, how many products do we have at $10 vs. at $20? Right click on Price and click “Convert to Dimension” or drag it from the Tableau Measures pane to the Tableau Dimensions pane.
- Now, remove the old green pill for Unit Price and drag out our newly created Tableau Dimension for Unit Price to the Rows shelf. You’ll see that it creates a row for every price in the data set. The Product Category headers are still across the top.
- When you drag out Number of Records from the Tableau Measures pane and drop it on the Text Mark card, you will now see the number of units by department per price point. We’ve now successfully swapped Tableau Measures and Tableau Dimensions and we are starting to see the versatility and flexibility that Tableau allows.
- Note that Number of Records is a standard feature of Tableau. In every workbook you will ever create, Tableau will calculate the number of records. It’s just a count of every instance or record in the dataset. It’s extremely useful, particularly if you are working with databases. It enables you to ask “how many” of any other Tableau dimension in your data.
We hope you learned a lot about Tableau dimension vs measure. To learn more Tableau tricks and tips, be sure to checkout our virtual Tableau courses.