[Qgis-user] labels: avoid duplicated labels

[Goyo]

I realize now that different maps will use different
fields/expressions for labelling so requiring different queries. Maybe
this feature can be added to the labelling engine but it would take
time.

Goyo

2013/10/14 Duarte Carreira <DCarreira at edia.pt>:
> Goyo, while I enjoy working with postgis a lot, the reality is I cannot expect "my" users to hack a sql view each time they need to label a map. It is not feasible to anticipate all situations and just create new items in my database to handle each one. It's difficult enough to manage the data as it is.
>
> I will just get a call or email asking how can the multiple labels be avoided, and there is no easy answer for that. The answer I've come up with is to select the features I want to label, and create a new layer in qgis with the corresponding query, remove the symbol and label it - much like the old label type layers in MapServer.
>
> Thanks,
> Duarte
>
> -----Mensagem original-----
> De: Goyo [mailto:goyodiaz at gmail.com]
> Enviada: quinta-feira, 3 de Outubro de 2013 20:19
> Para: Duarte Carreira
> Cc: Qgis (qgis-user at lists.osgeo.org)
> Assunto: Re: [Qgis-user] labels: avoid duplicated labels
>
> 2013/10/3 Duarte Carreira <DCarreira at edia.pt>:
>> Thanks for your suggestion.
>>
>> But this is not feasible. I cannot keep creating new spatial tables for cartographic purposes, I just can't pay the maintenance cost of that (updating).
>
> I was thinking of shapefiles and the like. With a spatial dabase it should be even easier. You can have a second geometry field and mantain it using a trigger or a script running in the background or at night or use a spatial view or just use multipolygons instead of (not in addition to) single polygons. The best solution depends on your typical workflow, the size of your data, etc.
>
> It also depends on which database engine you use. I have done this kind of things with spatialite and I think they can be done with postgis in a similar way. In particular I've found spatial views are a very powerful tool for cartography. I often want to show multipoint features as polygons (buffer(convexhull(geom), n)) or single points (centroid(buffer(convexhull(geom), n))) and I can do it even on the fly using the DB manager or the fast SQL layer plugin.
>
> Goyo
>
>> It is awkward to me missing this option...
>>
>> Duarte
>>
>>
>>
>> -----Mensagem original-----
>> De: Goyo [mailto:goyodiaz at gmail.com]
>> Enviada: quinta-feira, 3 de Outubro de 2013 16:57
>> Para: Duarte Carreira
>> Cc: Qgis (qgis-user at lists.osgeo.org)
>> Assunto: Re: [Qgis-user] labels: avoid duplicated labels
>>
>> 2013/10/3 Duarte Carreira <DCarreira at edia.pt>
>>>
>>> Hi there.
>>>
>>>
>>>
>>> Is there any option to avoid duplication of labels when several polygons have the same label?
>>
>> Convert your polygons to multipoligons, grouping by the field shown in the label.
>>
>> Goyo
>>
>