[Qgis-user] Line dissolve

[Andrea Giudiceandrea]

Nicolas Cadieux Mon, 30 Aug 2021 03:56:22 -0700
> This post explains what I would like.  It offer a QGIS 2 script that could 
> help. 
> https://gis.stackexchange.com/questions/198317/join-merge-lines-that-touch-and-intersect-in-qgis

Hi Nicolas,
I've also successfully ported that script to QGSI 3 as a processing script.
Since it appears the script was originally published on StackExchange by 
Jochen Schwarze, it has an implicit cc-by-sa license not really suitable 
for software code...

I'm trying to contact the author as a courtesy to know if he wants to 
publish himself the code with a GPLv2+ license on a collaborative 
version control website, maintain it and eventually let it available on 
plugins.qgis.org so I can submit my changes to him...

Anyway, you can find a version of the code modified by me to work as a 
processing script in QGIS 3.

It adds a subnet field to a line type layer. The field will contain the 
same unique progressive integer value for all the feature that are not 
disjoint (i.e. having any common node or are intersecting) to the other 
features.

You will find it at 
https://gist.github.com/agiudiceandrea/621e4f0f2804e49cbd6f2a4314c0e482

Be aware that for now the processing script doesn't have a proper 
progress and cancel feedback mechanism or any other sophisticated error 
checking and handling and I don't know what its performance is with 
layers containing a lot of features...

Regards.

Andrea