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<p>Thanks Charles,</p>
<p>This will be very useful. Nice to know I'am not the only one
going crazy with this!!!</p>
<p>Nicolas<br>
</p>
<div class="moz-cite-prefix">On 2021-08-30 4:42 p.m., Charles
Dixon-Paver wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAK2KqicSoitnwQH0xnxKkkJ2D=fD34DkR8yE7LPrjggfpUE4Bw@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">I thought this would be easily solved with an
expression but sadly I haven't been able to get reliable results
at all.<br>
<br>
My first thought was <span style="font-family:monospace">collect($geometry,filter:=intersects($geometry,geometry(@parent)))</span>
and when that didn't work I tried various aggregates and union
operations to no avail. Something like this might be useful if
you can get it into a usable form (I managed to get various
multigeometries in the form you are looking for but wasn't able
to do much with them and there seemed to be artifacts):<br>
<br>
<span style="font-family:monospace">collect_geometries(array_foreach(aggregate(layer:='lines',aggregate:='array_agg',expression:=$geometry,filter:=intersects($geometry,geometry(@parent))),@element))</span><br>
<br>
I was actually waiting for someone else to come up with a more
elegant solution, but it would probably also be possible to
identify intersecting features and get the minimum/ maximum
feature id for intersecting features with this:<br>
<br>
<span style="font-family:monospace">aggregate(layer:='lines',<br>
aggregate:='min',<br>
expression:="fid",<br>
filter:=intersects($geometry,geometry(@parent)))</span><br>
<br>
You could use that in the field calculator to create a field for
"grouping" various intersecting features to dissolve on, however
it's only going to identify the minimum of the currently
intersecting features so you would need to iterate through the
process multiple times. I can't think of an effective way to
implement a "while" conditional either.<br>
<br>
It's a pretty clanky way to do it, but if you are really
struggling I think it's possible.<br>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Mon, 30 Aug 2021 at 22:10,
Nicolas Cadieux <<a
href="mailto:njacadieux.gitlab@gmail.com"
moz-do-not-send="true">njacadieux.gitlab@gmail.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="auto">Hi,
<div><br>
<div>Seems like the plugin is available so I will try it
out. The ability to create multi-linestring out of any
touching lines (touch here means intersects at the first
or last node) would be nice to have it if I can include
it in a model. </div>
<div><br>
</div>
<div>My goal is for this model to work for anyone with a
basic install of QGIS LTR or 3.20 with minimal efforts
so I am trying to eliminate the need to rely on external
plugins or scripts.</div>
<div><br>
</div>
<div>This is also my first attempt with models. It’s a
learning curve but I am having fun… I think this
probably should have been a plugin but my knowledge of
GUI programming is basically 0. That will be for a next
project…</div>
<div><br>
<div dir="ltr">Nicolas Cadieux
<div><a href="https://gitlab.com/njacadieux"
target="_blank" moz-do-not-send="true">https://gitlab.com/njacadieux</a></div>
</div>
<div dir="ltr"><br>
<blockquote type="cite">Le 30 août 2021 à 14:59, David
Strip <<a href="mailto:qgis-user@stripfamily.net"
target="_blank" moz-do-not-send="true">qgis-user@stripfamily.net</a>>
a écrit :<br>
<br>
</blockquote>
</div>
<blockquote type="cite">
<div dir="ltr"> I looked at the source for this
plug-in and as far as I can tell it only merges
lines that meet at endpoints. It ignores
multi-lines, and only creates linestrings, so there
are no vertices of degree >2 (ie, no
junctions/forks). Also, the plug-in doesn't look for
intersections between vertices (since it only looks
to merge endpoints.)<br>
The StackExchange post appears to want
multi-linestrings, which gives forks and such. Is
that what you need? <br>
<br>
On 8/30/2021 5:27 AM, Nicolas Cadieux wrote:
<blockquote type="cite"> Hi,
<div>This is the plugin I was referring to. I
don’t see it in the current plugins
(experimental turned on) so I figured it’s QGIS
2 only.<br>
<div><br>
</div>
<div><a
href="https://github.com/ArMoraer/QGISMergeLines"
target="_blank" moz-do-not-send="true">https://github.com/ArMoraer/QGISMergeLines</a><br>
<br>
<div dir="ltr">Nicolas Cadieux
<div><a href="https://gitlab.com/njacadieux"
target="_blank" moz-do-not-send="true">https://gitlab.com/njacadieux</a></div>
</div>
<div dir="ltr"><br>
</div>
</div>
</div>
</blockquote>
<br>
</div>
</blockquote>
</div>
</div>
</div>
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</blockquote>
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</blockquote>
<pre class="moz-signature" cols="72">--
Nicolas Cadieux
<a class="moz-txt-link-freetext" href="https://gitlab.com/njacadieux">https://gitlab.com/njacadieux</a></pre>
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