![]() To calculate edge properties the programming pattern strategy ![]() You may want to implement your own builders that will build a graph compatible In the case with the director, only one builder exists: QgsGraphBuilder, The director sets the basic settings that will be used to construct a graphįrom a line vector layer, used by the builder to create the graph. There is only one Director for now: QgsVectorLayerDirector. A graph is constructed using a so-called Director. Vector layer attributes and length of an edge can be used as the propertiesĬonverting from a vector layer to the graph is done using the In the latter case the edge will be split and a new vertex added. Point a match will be found - the closest graph vertex or closest graph edge. Input vector layer any number of additional points. So two lines that have a common node become connected to each other.Īdditionally, during graph creation it is possible to “fix” (“tie”) to the If several nodes have the same coordinates then they are the same graph vertex. Nodes of the polylinesīecome graph vertexes, and segments of the polylines are graph edges. All further actions will use this graph,Īs a source we can use any polyline vector layer. The first thing you need to do - is to prepare input data, that is toĬonvert a vector layer into a graph. Use analysis results (for example, visualize them) General information īriefly, a typical use case can be described as:Ĭreate graph from geodata (usually polyline vector layer) RoadGraph core plugin and now you can use it’s methods in plugins orĭirectly from the Python console. The network analysis library was created by exporting basic functions from the Implement basic methods from graph theory (currently only Dijkstra’s The network analysis library can be used to:Ĭreate mathematical graph from geographical data (polyline vector layers) ![]() Tasks - doing heavy work in the background Expressions, Filtering and Calculating Values
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |