[Qgis-user] Join multiple Linestrings to single Linestring

[Richard McDonnell]

Another option, you could try is using the*Advanced Digitising Toolbar* 
under *View, Toolbars
*Select the lines you want to merge/Join and click *Merge Selected 
Features*.
This should also allow you to edit the DB directly from QGIS.
I have not tried it, so your issue with Multi-Lines instead of single 
linestrings may still apply.
You could still use the above example on the locally saved version of 
the table though and upload and overwrite the changed dataset.
Sorry I cant be of more help.
Reagrds,

Richard.
On 19/04/2017 14:07, Fuenfer-Koenigstein.Benjamin at swm.de wrote:
>
> Hi Richard,
>
> thanks for your suggestion! I think Dissolve won’t work for me as it’s 
> applied to the whole layer (hope I understood this right). I’m looking 
> for a way to easily merge certain linestrings when I, for example, 
> want to create one geometry by first creating a spline and then a 
> straight line feature. I will try out your workaround with local 
> files. But as the db-source is very large (> 500.000 rows) I’m happy 
> for any other suggestion to solve it directly in QGIS with db-source.
>
> Regards
>
> Benjamin
>
> *Von:*Richard McDonnell [mailto:richard.mcdonnell at opw.ie]
> *Gesendet:* Mittwoch, 19. April 2017 10:10
> *An:* David J. Bakeman; Fuenfer-Koenigstein.Benjamin G-PRA; 
> qgis-user at lists.osgeo.org
> *Betreff:* Re: [Qgis-user] Join multiple Linestrings to single Linestring
>
> Benjamin,
> You could try Dissolve, under Geoprocessing Tools, alternatively you 
> could try saving the dataset locally as a shapefile, edit using either 
> of the methods you outlined below, In relation to saving the edits 
> back to the table as linestring, use the DB Manager tool, select the 
> table you wish to update, tick the options you want, making sure both 
> *Replace destination Table (if exists) *and*Create single-part 
> geometries instead of multi-part* This has worked for me in the past, 
> admittedly for polygons, but it should also work for linestrings.
>
> Hope this helps,
>
> Richard.
>
> On 18/04/2017 17:24, David J. Bakeman wrote:
>
>     On 04/18/2017 02:17 AM,Fuenfer-Koenigstein.Benjamin at swm.de
>     <mailto:Fuenfer-Koenigstein.Benjamin at swm.de>  wrote:
>
>         Hi there,
>
>         I want to merge multiple linestrings with same start/endpoint to a single linestring (all lines within one layer). As I use a PostGIS source with geometry type linestring, it is important that the new geometry is still linestring and not multilinestring type. "Merge selected features" tool and "JOIN" in QAD-Plugin both create multilinestrings. Has anyone an idea how to directly merge into linestring or how to change geometry type after merging? Thanks for your suggestions!
>
>     I'm not sure I completely understand what you want but you could run
>
>     multipart to singleparts from the Vector/Geometry Tools menu on the
>
>     multilinestring layer to generate a layer with just linestrings.
>
>         Best regards
>
>         Benjamin
>
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> -- 
> *_Richard McDonnell_*
> *GIS Specialist PgD GIS AssocSCSI*
> *OPW FRM Data Management*
> *52 Stephens Green, Dublin 2.*
> TEL: 01 6476543
>
> Das Bild wurde vom Absender entfernt. <http://www.opw.ie/>
>

-- 
*_Richard McDonnell_*
*GIS Specialist PgD GIS AssocSCSI*
*OPW FRM Data Management*
*52 Stephens Green, Dublin 2.*
TEL: 01 6476543

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