Introduction
Introduced in Tableau 2022.4, this function allows you to determine if two spatial objects overlap.
The Syntax
INTERSECTS (<geometry1>, <geometry2>) – Which returns a Boolean (True/False) indicating if two spatial objects overlap.
Note, this function is supported for the following combinations.
Point/polygon
Line/polygon
Polygon/polygon
In this short article, I am going to demonstrate how you can use the INTERSECTS functions to determine overlapping spatial objects.
To demonstrate this, I will be using this sample data on ‘Health Facilities in Kibera’.
Therefore, I have plotted the facilities as shown in the map below.
Let’s say from this map, you would like to find out how many health facilities overlap a certain point on the map – it could be a school, area administrative office, or anything else.
You can do that by first creating a Buffer around that point. In this case, I am interested in a school which is at this geocodes (-1.31135,36.78935).
Therefore, I will create a buffer around this school using the following calculation.
(This calculation returns a 1,000 feet boundary around this imaginary school)
Drag the buffer calculation to the view (drag it to the marks layer) to show the 1,000 feet boundary around the school.
Create an INTERSECTS calculation using the health facilities points and the buffer calculation as shown below.
Add this calculation to the color shelf.
Add parameters to empower users dynamically adjust the number and units used to compute the buffer around your point of interest.
Note you can count the number of health facilities overlapping this point using the calculation below.
As well as compute the percent of the total facilities using the calculation below.
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