clusteringpointpoint-creationqgisvector
I have a set of coordinate points. The points are distributed in such a way that some points are clustered around a specific area. There is an option to find out mean coordinates(s) of the whole point layer.
I would like to know if there is any way in QGIS to find out the mean coordinates of the points from a specific area from a point layer.
You are now good to go. Points will be added wherever you click so long as your layer is highlighted in the layers-list. You can save your edits at any time by clicking on the little disk icon in the Digitizing toolbar (between the pen icon and three dots icon). When you are finished, toggle editting off by clicking on the pen icon again. If you toggle digitizing off without saving, you will be prompted to save your edits.
On the layer with the center point, you can use QGIS expressions. Get an array of the points from the same cluster using array_foreach and then for each of these points create create a line to the center and get it's length. You get an array of lengths. With array_mean, calculate the mean. This is how the expression looks like:
array_mean (
array_foreach (
overlay_nearest('points', $geometry, limit:=-1),
length (
make_line (
$geometry,
@element
)
)
)
)
Based on the data you have and how it is structured, you have to include a condition so that only points belonging to the same center are considered.
From the red center point, the expression generates a line to each of the white dots from the points layer, measures the length and gets the mean. The lines itself that you see here are generated with an expression based on this one with Geometry generator, see on the right side:
Best Answer
You need to do this in a two-stage process using the
Vector > Analysis Tools > Mean Coordinatestool in the second step. This tool will return the mean coordinates for sets of point within a layer if they have a unique"ID"field. So, if you have a polygon layer which defines your areas, do a spatial join (Vector > Data Management > Join attributes by location) to attribute your points with the polygon (area) id and then use the Mean coordinates tool, specifying the new field.You may already have unique
"ID"s or a polygon layer but if you do not you could create a fishnet (Vector > Research Tools > Vector Grid) to lay over the points as one method to define the areas. Alternatively, if your areas are defined by a raster layer, then you could use the Point sampling plugin to attribute the points based on your raster. Or, if you want to attribute them by location without a vector or raster layer, you will need to create an algorithm to give a new attribute based on the coordinates of each point (possibly using some modulus-based approach).