[GIS] Mean values of points within a polygon layer

point-in-polygonqgiszonal statistics

I have 2 shape files (1x points and 1x polygons). The points have different values (soil sampling results). What I want to do is to calculate the mean values of the points inside the different polygons (field border lines). In the end I can calculate percentaged values instead of the original values. These percentaged points I can interpolate.
Usually I did this with the following steps:

  1. converting point shape to grid
  2. Zonal Statistics to get the mean values
  3. Calculating the percentaged values with the mean
  4. Converting raster to points
  5. Interpolation (e.g. kriging)

This takes a very long time because the model I built is very slow. Is there another helpful tool that I could use (Zonal Statistics with vector points and vector polygone)?

Bye!

I gave Open Jump a chance and it works. What do you think, will there be a tool like that (it works like Zonal statistics just with a point and a polygon vector layer) one day in QGis?

Best Answer

If it does not need to be QGis I believe that Aggregation tool of OpenJUMP Plus can do exactly what you want. Tool is in Plugins - Analysis - Aggregation. With the selections used in the image below the tool adds a new column "Average" into the polygon layer and populates the field with average value of attribute "measure" of the points which are within each polygon.

enter image description here

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