clusteringqgis
I've basically got the same issue as Identifying cluster centroids using ArcGIS Desktop?, but can't find a way to transplant the ArcGIS solution to QGIS.
I have household-level geo data for 10 villages spread out across the country. I need to find the central point of these household clusters, so that I can create a 10km buffer around that central point.
I am new to QGIS.
ArcGIS has a few tools in the Spatial Statistics toolbox that might be useful.
Identifies the geographic center (or the center of concentration) for a set of features.
Identifies the location that minimizes overall Euclidean distance to the features in a dataset.
Identifies the most centrally located feature in a point, line, or polygon feature class.
I think the Mean Center would be most useful here when used with the Case Field option.
You can do the first by creating bins in a new field with the expression
ceil(id/30)
Where id is your sequential field. This returns 1 for the first 30 points, 2 for points 31-60 and so on.
Then, go into Symbology, choose Categorized, your bin field as the Value and classify.
This is what it'll look like:
Map result, showing 30 features per bin (note that my test data isn't ordered spatially).
You can do the second thing easily with this sql expression, using your bins:
select bins,st_convexhull(st_collect(geom)) as geom
from table
group by bins
Collects all the points by bin number and creates a convex hull around them. Result:
And here's a guide to running SQL queries within QGIS:
Best Answer
If it does not need to be QGIS you can do the task rather simply with OpenJUMP. In the beginning you have a road and a cluster of villages.
Select the villages and merge them to one multipoint feature. Tool opens with mouse right click.
Keep the new multipoint feature selected and find Geometry Functions toolbox from menu Tools-Analysis. Select the Centroid of A function, run it for selected features only and ask OpenJUMP to create a new layer for the result.
You can save the computed centroid of your cluster into shapefile if you want to continue with other tools than OpenJUMP. Or perhaps you want to continue and use the buffer tool first from Tools-Analysis-Buffer.