Aggregate Polygons

The Aggregate Polygon tool performs statistical analysis of polygons, e.g. count, sum, min, or max, and aggregates the information on polygons.

1. Explanation

With the Aggregate Polygons tool, data can be combined or aggregated between different polygon layers based on their spatial relationships. These spatial relationships are calculated using different statistical approaches. This technique is useful for analyzing and visualizing how different geographical entities interact, making them easier to analyze and interpret.

The example below shows the geometry of the Source Layer remains the same, while its attribute table will be enriched by aggregating information from the Area of Aggregation.

2. Example use cases

• Visualizing the number of parks per city district.
• Calculating the mean building size in an area.
• Aggregating population numbers on a hexagonal grid and calculating population densities.

3. How to use the tool?

1

Click on Toolbox .

2

Under the Geoanalysis menu, click on Aggregate Polygons.

Layer to aggregate

3

Select your Source Layer, which contains the data you like to aggregate.

4

Select on which Area Type you like to aggregate the source layer. You can choose between Polygon or H3 grid.

Polygon

Polygon

5

Select the Area Layer which contains the polygons on which you like to aggregate your point data.

H3 Grid

H3 Grid

5

Select the H3 Grid Resolution. You can choose resolutions between 3 (average edge length of 69km) and 10 (average edge length of 70m).

NOTE

To learn more about the H3 grid, you can visit the Glossary.

Statistics

6

Select the Statistic Method and Field Statistics (the field in the source layer that is used to group the aggregation.).

Available Statistics Methods are listed in the following. The available methods depend on the data type of the chosen attribute:

Method	Type	Description
Count	string,number	Counts the number of non-null values in the selected column
Sum	number	Calculates the sum of all the numbers in the selected column
Mean	number	Calculates the average (mean) value of all numeric values in the selected column
Median	number	Yields the middle value in the selected column's sorted list of numeric values
Min	number	Yields the minimum value of the selected column
Max	number	Yields the maximum value of the selected column

7

If you wish, you can enable the Weighted by Intersection Area by clicking on the options button . Therewith, aggregated values are weighted by the share of the intersection area between the Source Layer and the Aggregation Layer.

8

Click on Run.

Hint

Depending on the size of the datasets, the calculation might take some minutes. The status bar shows the current progress.

Results

9

As soon as the calculation process is finished, the resulting layer "Aggregation Polygon" will be added to the map. The result layer will consist of the information of the source layer and an additional column showing the results from the statistical operation. You can see the table by clicking on the polygon on the map.

Tip

Want to style your result layer and create nice-looking maps? See Styling.