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13 votes

Creating Isochrones in QGIS

Just recently, a new QGIS plugin, called OSM Tools, has been published. This plugin utilizes OpenRouteService API to compute routes and isochrones for various travel modes such as car, heavy vehicle, ...
Runge's user avatar
  • 401
11 votes

Creating Isochrones in QGIS

The plugin QNEAT3 offers a great tool for this creating isochrones or service areas offline based on your own network. You can run Iso-Areas as polygons or another algorithm: To get isochrones, ...
MrXsquared's user avatar
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10 votes
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Is there an optimal algorithm to find the longest shortest path in a network?

I think you may be looking for the Graph Diameter of your network. There are a couple of questions on stackexchange that mention this topic, e.g.: The time complexity of finding the diameter of a ...
mkadunc's user avatar
  • 2,071
10 votes
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Average walking distance

The solution: OD Matrix analysis You can do that with OD Matrix analysis (see here for the concept). This can be done in QGIS using the plugin QNEAT3. Once installed the plugin, use OD Matrix from ...
Babel's user avatar
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8 votes

Drawing lines between all possible combinations of points using ArcGIS Desktop?

WORKFLOW: arcpy.SpatialJoin_analysis("points","points", "D:/Scratch/many.shp","JOIN_ONE_TO_MANY","INTERSECT", search_radius="1000000 Meters") arcpy.SelectLayerByAttribute_management("many", "...
FelixIP's user avatar
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8 votes

Is there an optimal algorithm to find the longest shortest path in a network?

According to the Wikipedia page Longest path problem, this problem ... is NP-hard, meaning that it cannot be solved in polynomial time for arbitrary graphs unless P = NP. Stronger hardness ...
Alex Tereshenkov's user avatar
8 votes

Dragging all vertices at a given point programmatically in PyQGIS

This can be done using QGIS tools that you can enable programmatically. That is, there is no need to reinvent the wheel. Namely, you need to: Click on the Enable Topological Editing button in the ...
Germán Carrillo's user avatar
8 votes
Accepted

Generating dangle point for polyline in QGIS

Extract the vertices from road layer Explode the lines Join each line to the vertices, end points will get line count 1 and all other more than 1 Extract them
Bera's user avatar
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7 votes
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How to get lines and nodes around the confluence point in a network system (line shapefile)?

You work here with a Graph (Graph Theory) and your confluence point is simply a node with a degree (number of edges adjacent to that node) > 2. As you mentioned a Python tag, a solution in Python ...
gene's user avatar
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7 votes
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Merging close lines using v.clean

Buffering the road may be a solution to this problem. create a dissolved buffer of the road using around 20 unit map distance. import the layer into a postgis database and create the middle line ...
Amit Ghosh's user avatar
7 votes

Generating dangle point for polyline in QGIS

The specification of any polyline is a little optimistic (given the possibility of duplicate geometries), but for a topologically correct network it can be done using a "Virtual Layer" ...
Matt's user avatar
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7 votes

Automatically extend lines to node in QGIS

Use the following expression with Geoemtry Generator (visualizaiotn only) or Geometry by Expression (for actual geometries) on the line layer. See here for the difference between both options. Option ...
Babel's user avatar
  • 73.2k
6 votes

How to create an OD road distance matrix in QGIS?

UPDATE - QGIS3: Since this seems to be an important topic, I would like to share my answer on a similar question. If you are using the current version of QGIS (3), you can use the plugin QNEAT3. It ...
root676's user avatar
  • 2,385
6 votes

Creating Isochrones in QGIS

In QGIS 3 a Network analysis toolbox was added: You can create isochrones based on your network offline by choosing the "Fastest" path type to calculate: There are fewer settings than in ...
MrXsquared's user avatar
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6 votes
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How to connect nodes via shortest path along network lines with GRASS v.net modules?

I think I found an answer myself. The problem seems to be the topology of my network file. If I apply v.clean (snap) followed by v.clean (break or bpol), the nodes can be connected via v.net.steiner ...
Sophie Crommelinck's user avatar
6 votes

Shortest path using line layer QGIS

"Shortest path (point to point)" can do what you need. First, all your lines have to be in the same layer. Merge them if needed. Then, to avoid your error, your lines need to be connected ...
MrXsquared's user avatar
  • 34.9k
6 votes

Selecting certain road length around points in QGIS

This solution relies on two relatively new functions of QGIS expressions: array_sum(), avalilable since QGIS 3.18 and overlay_nearest(), available since QGIS 3.16. Calculate the total length of the ...
Babel's user avatar
  • 73.2k
6 votes

Generating dangle point for polyline in QGIS

To just visualize the dangles, use Geomtetry generator with this expression (see below to create actual geometries): difference ( collect_geometries ( array_foreach( array (...
Babel's user avatar
  • 73.2k
6 votes

Detecting and making all connected lines in the same direction in QGIS

Compare the azimuth of each line to the line group mean, and reverse the line in each group that deviate the most from the group mean: Refactor fields (or use two field calculators) to calculate: ...
Bera's user avatar
  • 74.9k
6 votes

Calculating distance between two closest points on graph in QGIS

Solution 1: Beeline distance Use distance matrix tool for a quick and dirty solution: ignoring the network, just beeline distance (for using network, see below). At least from your screenshot, this ...
Babel's user avatar
  • 73.2k
5 votes

Shortest path from points in one layer to points in another layer via roads in QGIS

You'll need some Python scripting because there is currently no GUI solution for this issue. To get you started, have a look at my point layer to route script for Processing which is based on the ...
underdark's user avatar
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5 votes
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distance matrix with a linear feature

I did have the same the same research question as you. I wanted to calculate the distance from archaeological sites to rivers. I did have access to a hydrological layer by INEGI. I did have rivers as ...
Gerardo Jimenez's user avatar
5 votes

Properter to get travel time as cost for network analysis

Here's a short Properter which I'm working on that might provide part of the answer. It aims to modify shortest path calculations for a road network by excluding freeways (because I'm using it for ...
Steve's user avatar
  • 361
5 votes
Accepted

Road design using Least cost path by longitudinal slope in ArcGIS Desktop?

Connecting 2 points on contours by straight line is not going to work, as seen on your second picture line crosses same contour twice. I also very much doubt that any out of the box tools can help you....
FelixIP's user avatar
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5 votes

Isochrones: v.iso.net

Althoug the question is a bit old, I would like to add some comment, in order to help those, who works on the same topic. As already was mentioned above, in order to properly generate isochrones, ...
Roman Bublyk's user avatar
5 votes

Creating line between point and all other possible points using FME

Funnily enough I did exactly the same thing, except this was for British football (soccer) teams. I wanted to figure out the shortest distance between each of them to see which team's supporters had ...
Mark Ireland's user avatar
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5 votes
Accepted

QGIS QNEAT3 AttributeError by creating isodistances/isochrones

You should once again think about the parameters you chose. QNEAT3 uses an interpolation raster for creating the isochrones on a network. You chose a cell size of 1000x1000m and entered a contour ...
root676's user avatar
  • 2,385
5 votes
Accepted

Counting the number of duplicated links in QGIS

You can use this simple expression to count lines in the same direction: array_length(overlay_equals(@layer,$id)) "geometry equals" respects the vertices order. So in case one line is drawn ...
MrXsquared's user avatar
  • 34.9k
5 votes

Generating dangle point for polyline in QGIS

Let's assume there is a polyline layer called 'lines_test2' with several features in it, see the image below. Step 1. Proceed with "Split with lines" tool to split the line layer with ...
Taras's user avatar
  • 33.3k
4 votes

Shortest path from points in one layer to points in another layer via roads in QGIS

I had a very similar problem, finding the amenities (restaurants etc) within a certain distance by road from access points along a bike path. I solved it with the toolbox script shown below, which is ...
Don's user avatar
  • 586

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