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Tableau Classification: Discrete vs. Continuous



Ryan Sleeper

Will you choose the green pill or the blue pill?

Another critical field classification is discrete vs. continuous. Ryan explains the single biggest myth in Tableau and his two rules of thumb for how to determine if a field should be discrete or continuous.

Hi, this is Ryan with Playfair Data TV, and in this video we’re going to talk about another major way that Tableau classifies each field in your data source – which is discrete vs. continuous.

Before I explain the difference, I want to point out something in the authoring interface because this is the number one myth in all of Tableau for users that are just getting started. Notice that every dimension in our data source here, which is in the Dimensions area of the Data pane, has a little icon next to it, and those icons are all color-coded blue.

And if you look down here in the Measures area of the Data pane, these are all the fields that Tableau classified as a measure. They also have an icon next to them, and they’re all color-coded green. For that reason, most people when they’re starting out believe that the blue color-coding represents dimensions, and the green color-coding represents measures.

That is absolutely not what the color-coding represents.

You can actually use dimensions and they can turn blue or green. So that is not what the color-coding means; the color-coding is related to this next classification that I’m going to discuss – which is discrete versus continuous.

Any time you see blue in Tableau, that means that the field is being used as a discrete field. When it’s used, it draws a header, and those headers can be sorted.

To help you wrap your mind around this topic, I’m going to show you the same two fields. So I’m going to build a visualization with the same two fields: Sales is my measure, and Order Date is my Dimension. But I’m going to make one change; I’m going to change the Order Date dimension from discrete to continuous.

So here’s the first example; we’ve got Sales as our measure on the Rows Shelf and we’ve got Order Date as a dimension on the Columns Shelf. Order Date is blue. When that is the case, each of those months is a discrete header; that’s why it’s called that. It’s drawing a discrete header, and those headers can be sorted.

This would be a good option if you were wanting to do an analysis like this where you’re comparing categories, and you want to sort them in descending order.

Here are those same two fields when I change Date from discrete to continuous. Any time you see green, that means the field’s being used as continuous. The difference with continuous is it draws a continuous axis, and that axis cannot be sorted; you cannot sort time.

So here’s what the chart looks like when I have Sales as a measure on the Rows Shelf and Month of Order Data is a continuous field on the Columns Shelf. Notice the difference this time; there’s a continuous axis across the bottom there. It goes in chronological order, and I cannot sort time.

So continuous fields would be a better option if I was wanting to look at some kind of trend over time, and create a line graph.

Another rule of thumb I’ve got for you; this is just something good to have in the back of your mind which will help you get to the correct result that you’re looking for in Tableau:

Discrete fields draw headers and they’re color-coded blue; those headers can be sorted.

Continuous fields draw axes. Those continuous fields are color-coded green, and you cannot sort them.

This has been Ryan with Playfair Data TV – thanks for watching!