QGIS Distance Matrix – Generate Line Geometry Output

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I have a series of Output Area centroids and I want to create a matrix of lines between each point (every point connected to every point), which is effectively what the distance matrix tool does (I think). But I also need the line geometry for visualisation purposes. Can anyone tell me how to do this?

Best Answer

As you have Distance matrix output, use its InputID and TargetID fields to build connecting lines.

Just open the Layer properties | Symbology and select Geometry generator.

If your original point layer name is points and it has id field (the one you used to create the Distance matrix), the expression would be:

make_line(geometry(get_feature('points', 'id', "InputID")), 
          geometry(get_feature('points', 'id', "TargetID")))

It will give you these connecting lines:

Related Solutions

qgis – Solving Problems with Distance Matrix in QGIS 2.83

I think all the problem lies in the fact that "Qgis 2.6 saves systematically Point layers into Multipoint layers which are ignored by distance matrix processing". I am working with Qgis 2.83 but I think the same thing aplies. This is what I did:

1) Using Vector/Geometry/multipart to single part I converted my river layers and my sites layer from multipoint to single point.

2) I re-ran Vector/Analysis tool/Distance matrix with the same parameters as in the question

Now I have the follwing results:

InputID, TargetID, Distance

3, 72738, 302.3181046

5, 77335, 2168.573439

6, 77944, 301.662413

7, 77928, 888.5274525

Using an external program I aanalize the data and now I now that 75% of my sites are within 0-,1500 to the nearest river and the rest are between 2500-2800 meters from the river. I located the problem following

http://www.qgistutorials.com/en/docs/nearest_neighbor_analysis.html

one of the comments stated the point/multipoint problem. Just to be in the safe side I saved the project and open a new one. I repeated the workflow and it worked again

[GIS] Distance Matrix output

If you don't mind a programmatic solution, you can do this easily in R with the dist function and the raster library. Example:

# make sure you have the raster library - you might also need rgdal
install.packages(c('raster', 'rgdal'))

# load the raster library
library(raster)

# define file path
shpFile <- "C:/path/to/shape/file.shp"

# load shapefile
shp <- shapefile(shpFile)

# convert SpatialPointsDataFrame to data.frame
shpDF <- as.data.frame(shp)

# get the distance matrix for coordinate sets
distMat <- dist(shpDF[,2:3])

# print results
print(distMat)

          1         2         3
2 192801.33                    
3 261837.21 133653.67          
4 240095.52  60905.06  86724.96

By default it will return the euclidean distance between each point in the shapefile. This should be used for data in a projected coordinate system. If you are using a geographic coordinate system, then look into the distHaversine function in the geosphere library.

Best Answer

Related Solutions

qgis – Solving Problems with Distance Matrix in QGIS 2.83

[GIS] Distance Matrix output

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