Splitting all lines in layer at vertices using QGIS

Question

I want to automatically split all lines in a QGIS layer at their vertices (like this).

I've done a Google search and found this article, which is quite close but the workflow is complicated. Because I'll have to train my co-workers (who are unfamiliar with GIS) to use this tool, I want something as simple as a plugin or something that doesn't require GRASS.

Since it's been a long time from 2010 - the time of the previous answer, I wonder if there is any better way to achieve the same result?

Answer 1

Try the "Explode lines" from the Processing Toolbox (Ctrl+Alt+T) will split all lines at their vertices to separate lines.

Menu Processing -> Toolbox. Type "explode" into the search field to find the function. Select your line layer from the dropdown and start. This will produce a new layer.

Selecting one or more lines from the line layer will produce a splitted layer with only these features, discarding the rest.

Note: As QGIS is moving fast, all infos below are outdated already.

I think Explode lines would be the the noob-solution through the SEXTANTE toolbox. QGIS Geoalgorithms > Vector geometry tools > Explode lines. Unfortunately, it does not seem to work at the moment, i get an error message only.

Traceback (most recent call last):
  File "path/.qgis//python/plugins\sextante\core\GeoAlgorithm.py", line 145, in execute
    self.processAlgorithm(progress)
  File "path/.qgis//python/plugins\sextante\algs\Explode.py", line 58, in processAlgorithm
    features = QGisLayers.features(layer)
NameError: global name 'layer' is not defined

A working solution is the Split Feature-Plugin from the "contributed" repository, which does the job for me.

In general I prefer sextante functions over separate plugins, cause the workflow with sextante is so much faster and produces no junk-files of intermediate steps (provided it works).

EDIT: Unfortunately, a lot of plugins were not moved to the official plugin repository yet, but are still only available through the "contributed" plugin repository: http://pyqgis.org/repo/contributed, which was removed from the default repositories list with version 1.8.

There you can download them individually and unzip them in your .qgis/python/plugins folder OR you add this address to your plugins repository list: Plugins -> Fetch python plugins -> Tab "Repositories" -> Add ... -> enter a name and the url.

Answer 2

1. Open/Create GRASS mapset (so you can run the tools on your data)
2. Open GRASS tools / Import the shapefile you want to split into the GRASS database
3. Run v.split.vert (set maximum number of vertices = 2)

Answer 3

lines = QgsProject.instance().mapLayersByName('layer_name')[0]

segment_list = []

for feature in lines.getFeatures():
    vertices = feature.geometry().asPolyline() # returns list of vertices comprising polyline
    for point in range(len(vertices)-1):
        segment = QgsFeature()
        segment.setGeometry(QgsGeometry.fromPolyline([QgsPoint(vertices[point]), QgsPoint(vertices [point+1])]))
        segment.setAttributes(feature.attributes())
        segment_list.append(segment.geometry())
        
print(segment_list)