Last year, Tableau introduced three spatial functions: Makepoint and Makeline (2019.2) and then Distance (2019.3). Then the spatial buffer calculation was released with Tableau 2020.1 and allows us to calculate the distance around a point location. In addition, no need to have a spatial file to use it, latitude and longitude columns will be enough! The buffer function creates a spatial object that will look like a circle mark on a map.

Buffer calculation in Tableau

The buffer calculation has 3 arguments

  • A spatial point
  • A radius (number)
  • A unit for the radius (miles, km, m or ft)

As I said above you don’t need a spatial file if you have the latitude and longitude columns in your dataset, you can use the Makepoint function to create a spatial point.

Makepoint calaculation

My objective is to plan a visit to a museum and see how many Street Art there is in the area. I have a dataset which contains the latitude and the longitude of the museums and the Street Art spots of Brussels.

First I created the spatial points for the street art spot with the Makepoint function. Then the buffer around the museums with the buffer function.

I drag the buffer field into the view, then I duplicate the longitude dimension. In the second mark card, I remove the buffer, I drag the street art spatial points and I obtain this map below.

spatial points

Next step is to transform this map into a dual axis to obtain the street art points overlapping the buffers of the museums.

dual axis for buffer calculation

I defined the size of my buffer to 200 meters. For more flexibility you can use a parameter instead. First step is to create a radius parameter like this one below and incorporate it into the buffer calculation.

size of buffer calculation

Dashboard example

If you are interested in Street Art and Brussels, have a look at this dashboard including the buffer calculation.

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