QGIS Clustering: Can I create heatmaps grouped by an attribute?

Question

I've got some data that looks like this:

Where the relevant attributes is called pci (and sepearately a signal level). I'd like to create a separate heat map for each pci value (e.g. pci=18).

Something sort of like this: But with one clear "pci" label per group, and more of a blobby rendering rather than point clusters. And ideally transparent overlap (blobs that touch each other would show a mix of colors).

But there is a trick: it would need a feature like pointcluster has with a radius. The same PCI value are reused elsewhere, so I'm only interested in points within about 500 meters of each other.

Is this something possible to configure QGIS to show? With some code?

Answer 1

You can imitate the behaviour of heatmaps (see here for details) using Geometry generator. To get several different such heatmaps, use different symbol layers and set a condition in the expression that generates the geometry.

1. Create a new symbol layer of type Geometry generator

2. The expression that creates the geometry looks like:

   case 
   when pci > 1 and pci <= 20  -- change these values to fit your needs
   then buffer ($geometry, 0.8) -- change the buffer size to fit your needs
   end
   

3. At the bottom of Layer styling, expand layer rendering and set the Blending mode for Feature to Screen. Works best if you use a very dark shade of the color. The denser points are, the lighter the area will be.

   Variant: use a very light shade of the color and use blending mode multiply. Play around with colors and blending mode to find an optimal solution.

4. Repeat steps 1 to 3. You can simply duplicate the symbol layer with the icon and then change the condition for pci and the color. All symbol layers will be shown one above the other.

Answer 2

Create a separate layer for each cluster by simply right-clicking the layer > Duplicate Layer. This will not duplicate data - simply the same file will be represented several times as different layers.

Then apply a heatmap style for each cluster - so have each cluster on a separate layer.