QGIS join by location not working between two shape files

Question

I am getting this weird error while using join attributes by location in QGIS, I have two layers - Source & Target. I am joining by target to source features using intersect option in join attributes by location.

Here is my script:

QgisAll_layers = QgsProject.instance().mapLayers().values()
path = QgsProject.instance().absolutePath() 
joined = str(path) + "//source_target_joined.shp"
unjoined = str(path) + "//source_target_unjoined.shp"

processing.run("qgis:joinattributesbylocation", {
                'INPUT': Source,
                'JOIN': Target,
                'PREDICATE': [0], 'JOIN_FIELDS': [], 'METHOD': 0, 'DISCARD_NONMATCHING': False, 'PREFIX': 'jj',
                'OUTPUT': joined, 'NON_MATCHING': unjoined})

Joined attribute table not having target field values.

I understand that the spatial join of features is not happening due to some reasons, it is not able to spatially identify the features in my script.

The Join Count is coming zero, even when I have tried to reproject both the vector layers to project CRS. I have tried to add spatial index to both the points but still it did not work.

Answer 1

It seems you are using point layers, are your geometries exactly coincident for the points you expect to join? For point geometries with several decimal figures, especially after reprojecting, it may be that they do not intersect. You could try Join by nearest and then filter out any joins that are above an acceptable distance threshold.