Concatenate points values in a field of a line

Question

I'd like to know how to concatenate points values (attribute data), using fields calculator of QGIS, putting this concatenation in a new field of the linear feature which connect some points of these.

For example, i'd like to get a new field called "name" in the linear layer, putting the concatenation of the field "type" of the points connected; from start point to the end point:

enter image description here

Any suggestions?

• Erik: Please check this question for a direction. It's no duplicate, but a rather similar one.

Answer 1

Try something like this in the field calculator in the lines layer

array_to_string(
 overlay_intersects(
 'layer',
 "type"
 ),
 ','
)

Replace layer with the layer name / id of the point layer.

Use this to return the data ordered by the position of the point in the line:

aggregate(
 layer:='Points layer name/id', -- set here the points layer name/id
 aggregate:='concatenate',
 expression:=to_string("type"), -- set here the field to be concatenated from points
 filter:=intersects(
 $geometry,
 geometry(@parent)
 ),
 order_by:=array_filter(
 array_foreach(
 generate_series(
 1,
 num_points(geometry(@parent))
 ),
 array(
 @element,
 point_n(
 geometry(@parent),
 @element
 )
 )
 ),
 intersects(
 $geometry,
 @element[1]
 )
 )[0][0],
 concatenator:=',' -- set here the concatenator
)

Result, red tags are the concatenated fields from points. result

• Mark: Is it possible that i get only the start point and the end point concatenated "c,e" (in the case of 3 points connected)?
• Mark: Sorry, I didn't make myself clear. I'd like to have an output as the question on top (all 3 vertices concatenated from start point to the end), but i'm trying your solution (array_to_string.....) and it doesn't work. Is it possible?
• Mark: It works! Thx! Is it also considered the order of the points in the concatenation (as in the image) or the "type" will be random?