[Qgis-user] Labeled grouping by geometry

Tue Jun 26 14:34:11 PDT 2018

Thanks for yours solutions. But I had found the best solution for me:

With an unique numeric field, such as id = 1, 2, ..., we can call it in the expression to distinguish one of overlapping lines.

In the Label with window, give expression:

CASE WHEN "id" = minimum("id" , group_by:=geom_to_wkt($geometry)) THEN "length"
ELSE NULL
END

No extra layer or fields.

Regards

----- Mensaje original -----
De: "Richard McDonnell" <richard.mcdonnell at opw.ie>
Para: "Emilio Abad Vidal" <eav at cesga.gal>, "Stefan Giese" <Stefan.Giese at wheregroup.com>
CC: Qgis-user at lists.osgeo.org
Enviados: Lunes, 25 de Junio 2018 13:32:40
Asunto: Re: [Qgis-user] Labeled grouping by geometry

Emilio, 
I have a partial solution, its not perfect. 
Create two new columns called:- 

    1. wnt with geomToWKT ( $geometry ) 
    2. disp_label with values of 0 as default, then update with the following 
    3. CASE WHEN count("wnt","wnt") > 1 THEN 1 ELSE 0 END 

What this does is to mark all duplicate geometries as 1 , which you can filter.... the only issue so far is to allow for the first value to be 0 , and mark the remaining! 
You can then use, under Rendering the data defined Show rendering, with a simple expression like "disp_label" = 0 you can only display the unique values! 

Apologies for it only being a partial solution, but maybe someone can improve on it! 
Regards, 

Richard. 

REFERENCED: 
https://gis.stackexchange.com/questions/72198/add-wkt-representation-of-the-geometry-as-field-in-qgis 
https://gis.stackexchange.com/questions/27822/identifying-duplicate-attributes-in-field-using-qgis 

On 25/06/2018 11:28, Emilio Abad Vidal wrote: 

Thank you very much Stefan,

but that solution means having one more layer. But my intention was to apply it in the labeling layer itself, if possible, of course.

Anyway, thanks for the reply

Emilio

----- Mensaje original -----
De: "Stefan Giese" <Stefan.Giese at wheregroup.com> Para: "Emilio Abad Vidal" <eav at cesga.gal> , Qgis-user at lists.osgeo.org Enviados: Lunes, 25 de Junio 2018 11:58:03
Asunto: Re: [Qgis-user] Labeled grouping by geometry

Hola Emilio, 

you can try do generate a new virtual Layer with a union of the geometry grouped by the geometry itself and use this one for labeling. The following statement will define your new virtual layer: 

select mylayer.labelfield, st_union( mylayer .geometry) from mylayer group by mylayer .geometry 

The result will be a new layer with no double geometries. 

Hope this helps 

Best regards 

Stefan 
Mit freundlichen Grüßen
Stefan Giese
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Am 25.06.2018 um 10:32 schrieb Emilio Abad Vidal: 

Hello everyone,

I have a problem and I can not find the solution. I would appreciate any help.

I have a layer of lines that represent stretches of electrical conductors. These sections have a point of origin and an end point. One of its attributes is the length of each of the sections.

Some of these sections have the same point of origin and the same ending point, so when I label these lines by their length, this repeated data appears for each of the lines and the data is repeated.

I need that when labeling the layer, only the label of one of the lines appears, that is, that the distance between each of the points is represented. I have tried to do it by means of a labeling based on rules, and some function of aggregation by geometry, so that only one label is shown for each space between points.

I do not get it, so I would appreciate any help to solve this problem.

Thank you very much in advance and greetings 
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Richard McDonnell 
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On 25/06/2018 11:28, Emilio Abad Vidal wrote: 