I'm working through an XY problem, with the end goal of effectively visualising data representing different journeys.

Given I have ordered data of the various positions (each with a time stamp) along the journey, I am considering using a MultiPoint layer, with each feature representing a journey, and each point a position along that journey.

I have written minimal (but verbose to convey intent) code below to generate a MultiPoint layer and visualise some dummy journeys as points.

My question: Is it possible to visually connect each pair of adjoining points with a line (or better still an arrow)? If so, how would I extend the following code to do this using PyQGIS?

I need to automate this, at the time the layer is created, and I don't want to rely on external plugins.

    from collections import namedtuple

    from qgis.core import QgsFeature, QgsField, QgsGeometry, QgsPointXY, QgsProject, QgsVectorLayer
    from qgis.PyQt.QtCore import QVariant

    # Create a new multipoint layer
    layer = QgsVectorLayer('MultiPoint?crs=EPSG:4326', "Journeys", 'memory')

    # Define attribute table headers
    field_headers = [
        QgsField('journey_id', QVariant.String),
        QgsField('positions [(lat, long, time_step), ...]', QVariant.String),
    layer_provider = layer.dataProvider()

    # Define sample data for 2 journeys
    Position = namedtuple('Position', 'lat long time_step')
    journeys = [
        ('journey_1', [Position(10, 0, 1), Position(1, 1, 2), Position(3, 0, 3)]),
        ('journey_2', [Position(-5, -5, 1), Position(2, 2, 2), Position(-4.5, 9, 3)]),

    # Create feature for each journey
    features = []
    for journey in journeys:
        journey_id, positions = journey

        # Create points list from positions
        points = [QgsPointXY(p.lat, p.long) for p in positions]

        # Create feature from points list
        feature = QgsFeature()

        # Add entry to attributes table
            ", ".join(f"({p.lat}, {p.long}, {p.time_step})" for p in positions),


    # Add features to layer, update, and commit

    # Add layer to legend
  • If you know this is an XY problem, then what is the X?
    – Vince
    Feb 1, 2019 at 20:20
  • I've played around with your data. IMO it would be easier to put the points from one journey not as an multipoint. Use instead point with to columns journey_id and time_stamp (or order), which you now put together in one field. Then it's easy to connect the points with arrrows, e.g. we can use the geometry generator to do it
    – eurojam
    Feb 2, 2019 at 6:27
  • @Vince The X is "effectively visualising data representing different journeys"
    – Jonny
    Feb 4, 2019 at 11:08

1 Answer 1


How married are you to the idea that MultiPoints are the best data type for your problem? I've created Trajectools a plugin that deals specifically with movement data: https://github.com/anitagraser/qgis-processing-trajectory and it creates LineStringM features. The advantage is that we can retain all timestamp information by storing each location's timestamp in the line node's m value.

Here's a screenshot from a recent post which shows movement speed encoded using color along the trajectory:

enter image description here

You can look at the code an borrow whatever you need.

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