Clustering Points within a map using centroids

If there are too many points on a map the map can become difficult to read. At these times, it can be helpful to cluster related points.

This can often be accomplished by using the center point of a shape file.

Load a polygon boundary file

The boundary files used to create a polygon on a map also contain fields for the latitude and longitudinal center of each shape.

For example, in the ZipBoundary.QVD the field ZipCenterLat and ZipCenterLng represent the center point of each Zip Code.

Create a QlikMaps for Points map

Insert the value that ties the shape to your data model in to the Dimension field.

For example, If each one of the points you wanted to cluster were associated with a zip code and you used the ZipBoundary.qvd file, Zip would be your Dimension.

In the Latitude and Longitude expression boxes, use the ZipCenterLat and ZipCenterLng fields from the ZipBoundary.QVD.

Use an expression to differentiate the points

There are a number of ways to differentiate the points.

The Size expression could be used to increase the size of the point based on how many points it represents. For example, Count(Salesman) would increase the size of the point in pixels based on the number of Salesman associated with that Zip Code in the data model.