[Qgis-user] Applying a label to a point in a series of points

[Brent Wood]

Hi & welcome...

I find this aspect is better addressed as a data management issue rather that a labelling one.

If your data is managed in database tables (Postgis, Spatialite, MariaDB/MySQL are the obvious free ones that work well with QGIS) then appending new points to existing lines and making lines from points is simple spatial data management. You can also set up a "view" - essentially a stored query acting like a physical table of data - returning, for example, the last point in a linestring.

If such a view is opened in QGIS with a label as well as the linestring itself without a label, both set to auto refresh every few seconds, then adding a point to a line in the db will be shown on the map automatically in both map layers as QGIS reloads the layer. The labelled point will move across the map as data is added to the db. This mimics the appearance of a GPS point moving on the map, but the data is read from the db instead of a live GPS.

Cheers,

Brent Wood

Principal Technician, Fisheries
NIWA
DDI:  +64 (4) 3860529
________________________________
From: QGIS-User <qgis-user-bounces at lists.osgeo.org> on behalf of Phil via QGIS-User <qgis-user at lists.osgeo.org>
Sent: Friday, 28 November 2025 10:56
To: qgis-user at lists.osgeo.org <qgis-user at lists.osgeo.org>
Subject: [Qgis-user] Applying a label to a point in a series of points

Hello everyone,

I'm new to QGIS and started experimenting a couple of days ago.

I have created three layers in addition to the map layer.

1. My home location.

2. A csv file of aircraft locations.

3. A trail that joins points of the same aircraft to form a line. I have
a label on each of these trails.

I'm happy with the results so far.

Ideally, I'd like to label the first and last points in a trail instead
of all points as I have now.  For example, if an aircraft has only been
logged once then that point should be labelled. If I have logged the
same aircraft multiple times then only the first last points should be
labelled.

My AI friend has tried to help by providing an assortment of label rules
but nothing has worked.

Here are the first 3 lines of 142 that I'm working with:

TIMESTAMP,AC_ID,LAT,LON
2025-11-21 23:55:36,71BE35,-33.962925,151.182806
2025-11-22 00:24:00,E80445,-33.958462,151.178686
2025-11-22 00:37:30,A47FDE,-33.971508,151.182120

I'll be grateful for any advice offered.

  --

Regards,
Phil

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Brent Wood
Principal Technician - GIS and Spatial Data Management
+64-4-386-0529
301 Evans Bay Parade, Greta Point, Hataitai, Wellington, New Zealand
Earth Sciences New Zealand
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