mapmatcher.py 文件源码

def getNetworkGraph(segments,segmentlengths):
    """
    Builds a networkx graph from the network file, inluding segment length taken from arcpy.
    It selects the largest connected component of the network (to prevent errors from routing between unconnected parts)
    """
    #generate the full network path for GDAL to be able to read the file
    path =str(os.path.join(arcpy.env.workspace,segments))
    print path
    if arcpy.Exists(path):
        g = nx.read_shp(path)
        #This selects the largest connected component of the graph
        sg = list(nx.connected_component_subgraphs(g.to_undirected()))[0]
        print "graph size (excluding unconnected parts): "+str(len(g))
        # Get the length for each road segment and append it as an attribute to the edges in the graph.
        for n0, n1 in sg.edges_iter():
            oid = sg[n0][n1]["OBJECTID"]
            sg.edge[n0][n1]['length'] = segmentlengths[oid]
        return sg
    else:
        print "network file not found on path: "+path