Project: QGIS
Version: 2.14.0
QGIS 2.14 Processing now incorporates v.net GRASS modules (only for GRASS7). Those modules are a set of algorithms that perform on graph line vector layers (networks). A graph is a set of vertices (or nodes or points) linked together with a set of edges (or arcs or lines). The set of edges is often called a network.
Thanks to v.net modules, you can easily calculate le shortest path between a set of nodes on the network or even compute the isochrone map from a set of central points. you can also easily solve the complex travelling salesman problem from a network and a set of travel nodes.
v.net algorithms often use a line vector layer (for the network) and a point layer which represents the nodes you want to use for the computation. Be sure to use a true graph line vector layer for the network layer (edges need to be connected on vertex without intersection between edges) to avoid problems. You can also use any network layer attribute for cost calculation (the content of the attribute is used to calculate the travel cost of the edge).
Here is a quick summary of the different algorithms that have been included into Processing:
- v.net.alloc: allocates subnets from nearest centres.
- v.net.allpairs: Computes the shortest path between all pairs of nodes in the network.
- v.net.arcs: Creates arcs from a file of points.
- v.net.articulation: Computes the articulation points in the network.
- v.net.bridge: Computes bridges of the network.
- v.net.centrality: Computes degree, centrality, betweenness, closeness and eigenvector centrality of each node of the network.
- v.net.components: Computes strongly and weakly connected components in the network.
- v.net.connect: Connects points (nodes) to nearest arcs in a network (and add edges if necessary).
- v.net.connectivity: Computes vertex connectivity between two sets of nodes in the network.
- v.net.distance: Computes the shortest path via the network between two sets of nodes.
- v.net.flow: Computes the maximum flow between two sets of nodes in the network.
- v.net.iso: Computes the isochrone map of the network from a set of nodes.
- v.net.nodes: Extracts nodes of a network/graph layer.
- v.net.nreports: Reports information about the nodes
- v.net.path: Find the shortest path on the network between two nodes.
- v.net.report: Reports information about the edges of a network.
- v.net.salesman: Computes the travelling salesman path from a set of nodes on the network.
- v.net.spanningtree: Computes the Spanning tree of a network.
- v.net.steiner: Creates a Steiner tree for the network and given nodes.
- v.net.visibility: Performs visibility graph construction.
Use the "Help" tab on each of the v.net Processing algorithm to directly read the official GRASS7 documentation for more information.
This feature was developed by Médéric Ribreux