Connecting points by lines using QGIS?

Question

I have a .shp file, where I want to connect all points (approx. 100) by lines. I have a data field with the order (i.e. 1, 2, 3, ...).

I have tried PointConnector and Points2One, maybe I am using them wrong, but I am not able to get any results.

In my searches, I've found mention of the plugin points to paths, but that seems to be gone?

I'm using QGIS 2.6.1

Answer 1

First, you can still use the PointsToPaths-Plugin (https://plugins.qgis.org/plugins/pointstopaths_v02/). Maybe you must enable the option "Show also experimental plugins" under Plugins > Manage and Install Plugins (Plugin Manager) > Settings.

Second, ensure that your data field with the order has a numeric-type (e.g. integer, ...)

I tried to create lines from a point shape with my QGIS-Version (2.0.1) and everything was fine. Here a screenshot:

Maybe this helps!

Screenshot with the results of the test_coords shape:

Answer 2

The MMQGIS plugin has a menu entry Create -> Hub Lines. This should do what you want.

It needs two layers (start and destination), so you might have to add your point layer twice to the canvas.

Answer 3

A basic approach would be:

1. create a vector-writer for a new shapefile (see Cookbook, Section "Writing Vector Layers", 2nd example) as (multi)line/polygon or whatever you need (see enums)
2. load your point layer from iface.legendInterface().layers()
3. iterate through your points and add the geometry feature in your new shape

€: just for fun:

from PyQt4.QtCore import *

# easy 2 config vars
myPath = "/media/ymirsson/MyData/GIS/tmp/"
myPts = "test_coords.shp"
myLines = "test_lines.shp"
sortField = "No"
myCRS = "25832"

# load the points layer
myPtsLayer = QgsVectorLayer(myPath + myPts, "My Points", "ogr")

# field def. 4 lines-layer
fields = QgsFields()
fields.append(QgsField("id", QVariant.Int))
fields.append(QgsField("name", QVariant.String))

# create writer
writer = QgsVectorFileWriter(myPath + myLines, "utf-8", fields, QGis.WKBLineString, QgsCoordinateReferenceSystem(int(myCRS), QgsCoordinateReferenceSystem.EpsgCrsId), "ESRI Shapefile")

if writer.hasError() == QgsVectorFileWriter.NoError:
    # featureobject to list
    features = myPtsLayer.getFeatures()
    Points=([])
    for feature in features:
        geom = feature.geometry().asPoint()
        sortID = feature.attributes()[myPtsLayer.fieldNameIndex(sortField)]
        Points.append([sortID,geom])
    Points.sort()

    # create lines
    for i in range(1,len(Points)):
        Line = QgsFeature()
        Line.setGeometry(QgsGeometry.fromPolyline([Points[i-1][1], Points[i][1]]))
        Line.setAttributes([i,str(Points[i-1][0]) + " to " + str(Points[i][0])])
        writer.addFeature(Line)
    # don't forget the last one -.-
    Line = QgsFeature()
    Line.setGeometry(QgsGeometry.fromPolyline([Points[len(Points)-1][1], Points[0][1]]))
    Line.setAttributes([len(Points),str(Points[len(Points)-1][0]) + " to " + str(Points[0][0])])
    writer.addFeature(Line)

# flush 2 disk
del writer

# load both layers into qgis-project
QgsMapLayerRegistry.instance().addMapLayer(myPtsLayer)
QgsMapLayerRegistry.instance().addMapLayer(QgsVectorLayer(myPath + myLines, "My Lines", "ogr"))

print "Done .. "