Translating point geometries and label placement conditioned by data fields values of two different layers

Question

As you can see in the screenshot, I have a HOUSENUM point geometry layer with the following data fields ID_HOUSENUM (corresponding to the portal text), ID_STREET (corresponding to the street code it belongs to) and ID_PARCEL (corresponding to the property it belongs to).

Each HOUSENUM is an individual point overlapped with each other.

Based on these data fields, how could we transfer the point geometries to the inner edge of each PARCEL taking into consideration the PARCEL it belongs to and the nearest STREET it belongs to. I show a screen shot with the expected result:

Features geometries are as follows:

• HOUSENUM → point
• PARCEL → irregular polygon
• STREET → polyline

Answer 1

This expression breaks the boundary of the parcel polygons into line segments, then finds the segment whose centroid is closest to the corresponding street in the address of the point. The centroid of that segment is then returned as the location to place the label.

The expression to apply on the point layer:

QGIS >=3.28

with_variable('street',
    get_feature('streets', 'name', "street"),   -- where 'streets' is the name of the streets layer and 'name' is the attribute field containing the name/code of the street
    with_variable('bnd',
        boundary(           -- get the boundary of the parcel as a line
            geometry(
                get_feature('parcels', 'parcel', "parcel") -- where 'parcels' is the name of the parcel layer and 'parcel' is the attiribute field containing the name/code of the parcel
            )
        ),
        with_variable('segments', geometries_to_array(segments_to_lines(@bnd)),       -- break boundary into segments and convert multiline to an array of individual geometries
            with_variable('dists',
                array_foreach(        -- loop over the array of geometries and get the distance from the centroid to the corresponding street
                    @segments,
                    distance(geometry(@street), centroid(@element))
                ),
                -- get the position in the array of the shortest distance and then use that position to find the geometry in the @segments array
                centroid( array_get(@segments, array_find(@dists, array_min(@dists))) )
            )
        )
    )
)

In the image, the blue points are the originals, and the red points signify the location of the label. I used points to make things clearer visually, but the same expression can be used in the Geometry Generator of the label placement options.

An adaptation to the expression to move the point a set distance inside the parcel:

with_variable('street',
    get_feature('streets', 'name', "street"),
    with_variable('bnd',
        boundary(
            geometry(
                get_feature('parcels', 'parcel', "parcel")
            )
        ),
        with_variable('segments', geometries_to_array(segments_to_lines(@bnd)),
            with_variable('dists',
                array_foreach(
                    @segments,
                    distance(geometry(@street), centroid(@element))
                ),
                -- make a line between the parcel centroid and the centroid of the segment
                with_variable('line',
                    make_line(centroid(@bnd), centroid( array_get(@segments, array_find(@dists, array_min(@dists))) )),

                    -- cut this line short by a specified distance (5m) and get its endpoint (the new label position)
                    end_point(line_substring(@line, 0, length(@line) - 5))
                )
            )
        )
    )
)

Without the use of geometries_to_array function (QGIS <3.28)

The second expression rewritten for versions of QGIS prior to the geometries_to_array function being added:

with_variable('street',
    get_feature('streets', 'name', "street"),
    with_variable('bnd',
        boundary(
            geometry(
                get_feature('parcels', 'parcel', "parcel")
            )
        ),
        
        with_variable('segments', 
            array_foreach(
                generate_series(1, num_geometries(segments_to_lines(@bnd))), 
                geometry_n(segments_to_lines(@bnd), @element)
            ),
            with_variable('dists', 
                array_foreach(        -- loop over the array of geometries and get the distance from the centroid to the corresponding street
                    @segments,
                    distance(geometry(@street), centroid(@element))
                ),
                -- make a line between the parcel centroid and the centroid of the segment
                with_variable('line',
                    make_line(centroid(@bnd), centroid( array_get(@segments, array_find(@dists, array_min(@dists))) )),

                    -- cut this line short by a specified distance (5m) and get its endpoint (the new label position)
                    end_point(line_substring(@line, 0, length(@line) - 5))
                )
            )
        )
    )
)