Now that we have our final constraint layer, which can be used as a simple mask, we can proceed and create our factors. First, we can remove every intermediary layer we worked with, as our factors use different vector layers as input:
- Open the geonames, rivers, waterbodies, and roads vector layers.
- Filter the geonames layer to only show the seats of the administrative regions. The correct expression is "featurecod" LIKE 'PPLA%' or "featurecode" LIKE 'PPLA%' depending on which version we use.
- Filter the roads layer to only show motorways and highways. Such a filter can be applied with the expression "fclass" LIKE 'motorway%' OR "fclass" LIKE 'primary%'.
- Get the mean point of the seats of the filtered settlements by using the QGIS geoalgorithms | Vector analysis...
