Or you could use v.distance from GRASS (either through Processing or the QGIS-GRASS plugin):
http://grass.osgeo.org/grass64/manuals/v.distance.html
With the “output”-option it produces lines.
Cheers
Stefan
From: qgis-user-bounces at lists.osgeo.org [mailto:qgis-user-bounces at lists.osgeo.org] On Behalf Of Alexandre Neto
Sent: 10. mars 2015 10:32
To: Raymond Nijssen
Cc: QGIS User
Subject: Re: [Qgis-user] Fwd: Visualize Distance matrix
If your data is in a Spatialite or a Postgis database, it's quite easy to achieve what you seek.
All you need to do is create a SQL query similar to this one in DB Manager:
SELECT
a.gid as dep_id,
b.gid as dest_id,
ST_Distance(a.geom, b.geom) as distance,
ST_MakeLine(a.geom, b.geom) as geom
FROM
my_table as a, my_table as b
WHERE
a.gid > b.gid
Note: This is the postgis version, not sure if the same function applies to spatialite
Add it to the map canvas by using dep_id as unique value column and geom as geometry column.
Hope it helps.
Alexandre Neto
On Tue, Mar 10, 2015 at 8:08 AM, Raymond Nijssen <r.nijssen at terglobo.nl<mailto:r.nijssen at terglobo.nl>> wrote:
Hi Joris,
I dont know about that plugin, but i would write a little script for that like this:
# get active (point) layer as input
inputlayer = iface.activeLayer()
# create new memory layer for output
outputlayer = QgsVectorLayer("Linestring", "distance_lines", "memory")
outputprovider = outputlayer.dataProvider()
# loop all points
iter = inputlayer.getFeatures()
for feature in iter:
p1 = feature.geometry().asPoint()
iter2 = layer.getFeatures()
for feature2 in iter2:
p2 = feature2.geometry().asPoint()
if not p1 == p2:
# create new line
l = QgsGeometry.fromPolyline([p1,p2])
feat = QgsFeature()
feat.setGeometry(l)
outputprovider.addFeatures([feat])
outputlayer.commitChanges()
outputlayer.updateExtents()
# add to map
QgsMapLayerRegistry.instance().addMapLayer(outputlayer)
Good luck,
Raymond
On 09-03-15 18:18, Joris Hintjens wrote:
Thanks Raymond, but what I need is the distance from every point in a layer to every other point. That is what “distance matrix” gives me.
Then, I want to plot every distance line (as a seperate layer?) on the map.
Joris
Begin doorgestuurd bericht:
Datum: 9 maart 2015 15:53:56 CET
Van: Raymond Nijssen <r.nijssen at terglobo.nl<mailto:r.nijssen at terglobo.nl>>
Aan: qgis-user at lists.osgeo.org<mailto:qgis-user at lists.osgeo.org>
Onderwerp: Antw.: [Qgis-user] Visualize Distance matrix
Hi Joris,
Not sure if I understand your question, but if you want to do a distance calculation for all points in a point layer to a certain location you can use the field calculator in the attribute table window.
The expression should be:
distance($geometry ,geomFromWKT( 'POINT(0 0)' ))
to calculate all distances to coordinate 0,0.
Hope this helps you.
Raymond
On 09-03-15 15:13, Joris Hintjens wrote:
I feel stupid: I am stuck with what seems a basic operation..
I have a points layer, of which I want to visualize the distance matrix.
I can create the martini CSV.
I cannot create a distance hub layer with the MMQGIS plugin with From and To point from within the same layer.
Any help on how I ca get this result on my map?
PoinA——————>PointB
xxx Meter
and this for the entire matrix
thanks
Joris
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