Python networkx.dijkstra_path() Examples

def test_random_graph(self):

        def dist(a, b):
            (x1, y1) = a
            (x2, y2) = b
            return ((x1 - x2) ** 2 + (y1 - y2) ** 2) ** 0.5

        G = nx.Graph()

        points = [(random(), random()) for _ in range(100)]

        # Build a path from points[0] to points[-1] to be sure it exists
        for p1, p2 in zip(points[:-1], points[1:]):
            G.add_edge(p1, p2, weight=dist(p1, p2))

        # Add other random edges
        for _ in range(100):
            p1, p2 = choice(points), choice(points)
            G.add_edge(p1, p2, weight=dist(p1, p2))

        path = nx.astar_path(G, points[0], points[-1], dist)
        assert path == nx.dijkstra_path(G, points[0], points[-1]) 

def getEdgeHistogram(inGraph, refGraph):
    falsePositives = set(inGraph.edges()).difference(refGraph.edges())
    edgeHistogramCounts = {0:0}
    
    for fe in falsePositives:
        u,v = fe
        try:
            path = nx.dijkstra_path(refGraph,u,v)
            pathlength = len(path) -1 
            if pathlength in edgeHistogramCounts.keys():
                edgeHistogramCounts[pathlength] +=1
            else:
                edgeHistogramCounts[pathlength] = 0
            
        except nx.exception.NetworkXNoPath:
            edgeHistogramCounts[0] +=1
    return edgeHistogramCounts 

def test_random_graph(self):
        """Tests that the A* shortest path agrees with Dijkstra's
        shortest path for a random graph.

        """

        G = nx.Graph()

        points = [(random(), random()) for _ in range(100)]

        # Build a path from points[0] to points[-1] to be sure it exists
        for p1, p2 in pairwise(points):
            G.add_edge(p1, p2, weight=dist(p1, p2))

        # Add other random edges
        for _ in range(100):
            p1, p2 = choice(points), choice(points)
            G.add_edge(p1, p2, weight=dist(p1, p2))

        path = nx.astar_path(G, points[0], points[-1], dist)
        assert_equal(path, nx.dijkstra_path(G, points[0], points[-1])) 

def test_bidirectional_dijkstra(self):
        validate_length_path(
            self.XG, 's', 'v', 9, *nx.bidirectional_dijkstra(self.XG, 's', 'v'))
        validate_length_path(
            self.G, 's', 'v', 2, *nx.bidirectional_dijkstra(self.G, 's', 'v'))
        validate_length_path(
            self.cycle, 0, 3, 3, *nx.bidirectional_dijkstra(self.cycle, 0, 3))
        validate_length_path(
            self.cycle, 0, 4, 3, *nx.bidirectional_dijkstra(self.cycle, 0, 4))
        validate_length_path(
            self.XG3, 0, 3, 15, *nx.bidirectional_dijkstra(self.XG3, 0, 3))
        validate_length_path(
            self.XG4, 0, 2, 4, *nx.bidirectional_dijkstra(self.XG4, 0, 2))

        # need more tests here
        P = nx.single_source_dijkstra_path(self.XG, 's')['v']
        validate_path(self.XG, 's', 'v', sum(self.XG[u][v]['weight'] for u, v in zip(
            P[:-1], P[1:])), nx.dijkstra_path(self.XG, 's', 'v')) 

def test_bidirectional_dijkstra(self):
        validate_length_path(
            self.XG, 's', 'v', 9, *nx.bidirectional_dijkstra(self.XG, 's', 'v'))
        validate_length_path(
            self.G, 's', 'v', 2, *nx.bidirectional_dijkstra(self.G, 's', 'v'))
        validate_length_path(
            self.cycle, 0, 3, 3, *nx.bidirectional_dijkstra(self.cycle, 0, 3))
        validate_length_path(
            self.cycle, 0, 4, 3, *nx.bidirectional_dijkstra(self.cycle, 0, 4))
        validate_length_path(
            self.XG3, 0, 3, 15, *nx.bidirectional_dijkstra(self.XG3, 0, 3))
        validate_length_path(
            self.XG4, 0, 2, 4, *nx.bidirectional_dijkstra(self.XG4, 0, 2))

        # need more tests here
        P = nx.single_source_dijkstra_path(self.XG, 's')['v']
        validate_path(self.XG, 's', 'v', sum(self.XG[u][v]['weight'] for u, v in zip(
            P[:-1], P[1:])), nx.dijkstra_path(self.XG, 's', 'v')) 

def test_astar_undirected3(self):
        XG4=nx.Graph()
        XG4.add_edges_from([ [0,1,{'weight':2}],
                             [1,2,{'weight':2}],
                             [2,3,{'weight':1}],
                             [3,4,{'weight':1}],
                             [4,5,{'weight':1}],
                             [5,6,{'weight':1}],
                             [6,7,{'weight':1}],
                             [7,0,{'weight':1}] ])
        assert nx.astar_path(XG4,0,2)==[0, 1, 2]
        assert nx.astar_path_length(XG4,0,2)==4


# >>> MXG4=NX.MultiGraph(XG4)
# >>> MXG4.add_edge(0,1,3)
# >>> NX.dijkstra_path(MXG4,0,2)
# [0, 1, 2] 

def test_random_graph(self):
        """Tests that the A* shortest path agrees with Dijkstra's
        shortest path for a random graph.

        """

        G = nx.Graph()

        points = [(random(), random()) for _ in range(100)]

        # Build a path from points[0] to points[-1] to be sure it exists
        for p1, p2 in pairwise(points):
            G.add_edge(p1, p2, weight=dist(p1, p2))

        # Add other random edges
        for _ in range(100):
            p1, p2 = choice(points), choice(points)
            G.add_edge(p1, p2, weight=dist(p1, p2))

        path = nx.astar_path(G, points[0], points[-1], dist)
        assert_equal(path, nx.dijkstra_path(G, points[0], points[-1])) 

def test_bidirectional_dijkstra(self):
        validate_length_path(
            self.XG, 's', 'v', 9, *nx.bidirectional_dijkstra(self.XG, 's', 'v'))
        validate_length_path(
            self.G, 's', 'v', 2, *nx.bidirectional_dijkstra(self.G, 's', 'v'))
        validate_length_path(
            self.cycle, 0, 3, 3, *nx.bidirectional_dijkstra(self.cycle, 0, 3))
        validate_length_path(
            self.cycle, 0, 4, 3, *nx.bidirectional_dijkstra(self.cycle, 0, 4))
        validate_length_path(
            self.XG3, 0, 3, 15, *nx.bidirectional_dijkstra(self.XG3, 0, 3))
        validate_length_path(
            self.XG4, 0, 2, 4, *nx.bidirectional_dijkstra(self.XG4, 0, 2))

        # need more tests here
        P = nx.single_source_dijkstra_path(self.XG, 's')['v']
        validate_path(self.XG, 's', 'v', sum(self.XG[u][v]['weight'] for u, v in zip(
            P[:-1], P[1:])), nx.dijkstra_path(self.XG, 's', 'v'))

        # check absent source
        G = nx.path_graph(2)
        assert_raises(nx.NodeNotFound, nx.bidirectional_dijkstra, G, 3, 0) 

def pathStats(inGraph, refGraph):
    """
    Only returns TP, FP, numPredictions for each networks
    """
    falsePositives = set(inGraph.edges()).difference(refGraph.edges())
    truePositives = set(inGraph.edges()).intersection(refGraph.edges())
    numPredictions = len(inGraph.edges())
    nopath = 0
    yespath = 0
    edgeCounts = {0:0,2:0,3:0,4:0,5:0}    
    for fe in falsePositives:
        u,v = fe
        try:
            path = nx.dijkstra_path(refGraph,u,v)
            pathlength = len(path) -1
            yespath +=1
            if pathlength in edgeCounts.keys():
                edgeCounts[pathlength] +=1
            
        except nx.exception.NetworkXNoPath:
            nopath +=1

    edgeCounts['numPred'] = numPredictions
    edgeCounts['numTP'] = len(truePositives)
    edgeCounts['numFP_withPath'] = yespath
    edgeCounts['numFP_noPath'] = nopath
    return edgeCounts 

def test_astar_undirected3(self):
        XG4 = nx.Graph()
        edges = [(0, 1, 2), (1, 2, 2), (2, 3, 1), (3, 4, 1), (4, 5, 1),
                 (5, 6, 1), (6, 7, 1), (7, 0, 1)]
        XG4.add_weighted_edges_from(edges)
        assert_equal(nx.astar_path(XG4, 0, 2), [0, 1, 2])
        assert_equal(nx.astar_path_length(XG4, 0, 2), 4)

# >>> MXG4=NX.MultiGraph(XG4)
# >>> MXG4.add_edge(0,1,3)
# >>> NX.dijkstra_path(MXG4,0,2)
# [0, 1, 2] 

def test_cycle(self):
        C = nx.cycle_graph(7)
        assert_equal(nx.astar_path(C, 0, 3), [0, 1, 2, 3])
        assert_equal(nx.dijkstra_path(C, 0, 4), [0, 6, 5, 4]) 

def test_absent_source(self):
        # the check is in _dijkstra_multisource, but this will provide
        # regression testing against later changes to any of the "client"
        # Dijkstra or Bellman-Ford functions
        G = nx.path_graph(2)
        for fn in (nx.dijkstra_path,
                   nx.dijkstra_path_length,
                   nx.single_source_dijkstra_path,
                   nx.single_source_dijkstra_path_length,
                   nx.single_source_dijkstra,
                   nx.dijkstra_predecessor_and_distance,):
            assert_raises(nx.NodeNotFound, fn, G, 3, 0) 

def user_CFG_API(fcgnx, source_node_list, j):
    
    flag=False 
    for i in source_node_list:  
       if nx.has_path(fcgnx, i, j): 
          print (" {} ->  {}".format(i,j)) 
          #print (nx.dijkstra_path(fcgnx,i,j))               
          flag = True
          break
    return flag    
    
###
#  user trigger feature
### 

def propagation(input_power, con_in, con_out, dest):
    equipment = load_equipment(eqpt_library_name)
    network = load_network(network_file_name, equipment)
    build_network(network, equipment, 0, 20)

    # parametrize the network elements with the con losses and adapt gain
    # (assumes all spans are identical)
    for e in network.nodes():
        if isinstance(e, Fiber):
            loss = e.params.loss_coef * e.params.length
            e.params.con_in = con_in
            e.params.con_out = con_out
        if isinstance(e, Edfa):
            e.operational.gain_target = loss + con_in + con_out

    transceivers = {n.uid: n for n in network.nodes() if isinstance(n, Transceiver)}

    p = input_power
    p = db2lin(p) * 1e-3
    spacing = 50e9  # THz
    si = create_input_spectral_information(191.3e12, 191.3e12 + 79 * spacing, 0.15, 32e9, p, spacing)
    source = next(transceivers[uid] for uid in transceivers if uid == 'trx A')
    sink = next(transceivers[uid] for uid in transceivers if uid == dest)
    path = dijkstra_path(network, source, sink)
    for el in path:
        si = el(si)
        print(el)  # remove this line when sweeping across several powers
    edfa_sample = next(el for el in path if isinstance(el, Edfa))
    nf = mean(edfa_sample.nf)

    print(f'pw: {input_power} conn in: {con_in} con out: {con_out}',
          f'OSNR@0.1nm: {round(mean(sink.osnr_ase_01nm),2)}',
          f'SNR@bandwitdth: {round(mean(sink.snr),2)}')
    return sink, nf, path 

def test_dijkstra(self):
        (D, P) = nx.single_source_dijkstra(self.XG, 's')
        validate_path(self.XG, 's', 'v', 9, P['v'])
        assert_equal(D['v'], 9)

        validate_path(
            self.XG, 's', 'v', 9, nx.single_source_dijkstra_path(self.XG, 's')['v'])
        assert_equal(dict(
            nx.single_source_dijkstra_path_length(self.XG, 's'))['v'], 9)

        validate_path(
            self.XG, 's', 'v', 9, nx.single_source_dijkstra(self.XG, 's')[1]['v'])
        validate_path(
            self.MXG, 's', 'v', 9, nx.single_source_dijkstra_path(self.MXG, 's')['v'])

        GG = self.XG.to_undirected()
        # make sure we get lower weight
        # to_undirected might choose either edge with weight 2 or weight 3
        GG['u']['x']['weight'] = 2
        (D, P) = nx.single_source_dijkstra(GG, 's')
        validate_path(GG, 's', 'v', 8, P['v'])
        assert_equal(D['v'], 8)     # uses lower weight of 2 on u<->x edge
        validate_path(GG, 's', 'v', 8, nx.dijkstra_path(GG, 's', 'v'))
        assert_equal(nx.dijkstra_path_length(GG, 's', 'v'), 8)

        validate_path(self.XG2, 1, 3, 4, nx.dijkstra_path(self.XG2, 1, 3))
        validate_path(self.XG3, 0, 3, 15, nx.dijkstra_path(self.XG3, 0, 3))
        assert_equal(nx.dijkstra_path_length(self.XG3, 0, 3), 15)
        validate_path(self.XG4, 0, 2, 4, nx.dijkstra_path(self.XG4, 0, 2))
        assert_equal(nx.dijkstra_path_length(self.XG4, 0, 2), 4)
        validate_path(self.MXG4, 0, 2, 4, nx.dijkstra_path(self.MXG4, 0, 2))
        validate_path(
            self.G, 's', 'v', 2, nx.single_source_dijkstra(self.G, 's', 'v')[1])
        validate_path(
            self.G, 's', 'v', 2, nx.single_source_dijkstra(self.G, 's')[1]['v'])

        validate_path(self.G, 's', 'v', 2, nx.dijkstra_path(self.G, 's', 'v'))
        assert_equal(nx.dijkstra_path_length(self.G, 's', 'v'), 2)

        # NetworkXError: node s not reachable from moon
        assert_raises(nx.NetworkXNoPath, nx.dijkstra_path, self.G, 's', 'moon')
        assert_raises(
            nx.NetworkXNoPath, nx.dijkstra_path_length, self.G, 's', 'moon')

        validate_path(self.cycle, 0, 3, 3, nx.dijkstra_path(self.cycle, 0, 3))
        validate_path(self.cycle, 0, 4, 3, nx.dijkstra_path(self.cycle, 0, 4))

        assert_equal(nx.single_source_dijkstra(self.cycle, 0, 0), (0, [0])) 

def bellman_ford_path(G, source, target, weight='weight'):
    """Returns the shortest path from source to target in a weighted graph G.

    Parameters
    ----------
    G : NetworkX graph

    source : node
       Starting node

    target : node
       Ending node

    weight: string, optional (default='weight')
       Edge data key corresponding to the edge weight

    Returns
    -------
    path : list
       List of nodes in a shortest path.

    Raises
    ------
    NodeNotFound
        If `source` is not in `G`.

    NetworkXNoPath
       If no path exists between source and target.

    Examples
    --------
    >>> G=nx.path_graph(5)
    >>> print(nx.bellman_ford_path(G, 0, 4))
    [0, 1, 2, 3, 4]

    Notes
    -----
    Edge weight attributes must be numerical.
    Distances are calculated as sums of weighted edges traversed.

    See Also
    --------
    dijkstra_path(), bellman_ford_path_length()
    """
    length, path = single_source_bellman_ford(G, source,
                                              target=target, weight=weight)
    return path 

def test_dijkstra(self):
        (D, P) = nx.single_source_dijkstra(self.XG, 's')
        validate_path(self.XG, 's', 'v', 9, P['v'])
        assert_equal(D['v'], 9)

        validate_path(
            self.XG, 's', 'v', 9, nx.single_source_dijkstra_path(self.XG, 's')['v'])
        assert_equal(
            nx.single_source_dijkstra_path_length(self.XG, 's')['v'], 9)

        validate_path(
            self.XG, 's', 'v', 9, nx.single_source_dijkstra(self.XG, 's')[1]['v'])
        validate_path(
            self.MXG, 's', 'v', 9, nx.single_source_dijkstra_path(self.MXG, 's')['v'])

        GG = self.XG.to_undirected()
        # make sure we get lower weight
        # to_undirected might choose either edge with weight 2 or weight 3
        GG['u']['x']['weight'] = 2
        (D, P) = nx.single_source_dijkstra(GG, 's')
        validate_path(GG, 's', 'v', 8, P['v'])
        assert_equal(D['v'], 8)     # uses lower weight of 2 on u<->x edge
        validate_path(GG, 's', 'v', 8, nx.dijkstra_path(GG, 's', 'v'))
        assert_equal(nx.dijkstra_path_length(GG, 's', 'v'), 8)

        validate_path(self.XG2, 1, 3, 4, nx.dijkstra_path(self.XG2, 1, 3))
        validate_path(self.XG3, 0, 3, 15, nx.dijkstra_path(self.XG3, 0, 3))
        assert_equal(nx.dijkstra_path_length(self.XG3, 0, 3), 15)
        validate_path(self.XG4, 0, 2, 4, nx.dijkstra_path(self.XG4, 0, 2))
        assert_equal(nx.dijkstra_path_length(self.XG4, 0, 2), 4)
        validate_path(self.MXG4, 0, 2, 4, nx.dijkstra_path(self.MXG4, 0, 2))
        validate_path(
            self.G, 's', 'v', 2, nx.single_source_dijkstra(self.G, 's', 'v')[1]['v'])
        validate_path(
            self.G, 's', 'v', 2, nx.single_source_dijkstra(self.G, 's')[1]['v'])

        validate_path(self.G, 's', 'v', 2, nx.dijkstra_path(self.G, 's', 'v'))
        assert_equal(nx.dijkstra_path_length(self.G, 's', 'v'), 2)

        # NetworkXError: node s not reachable from moon
        assert_raises(nx.NetworkXNoPath, nx.dijkstra_path, self.G, 's', 'moon')
        assert_raises(
            nx.NetworkXNoPath, nx.dijkstra_path_length, self.G, 's', 'moon')

        validate_path(self.cycle, 0, 3, 3, nx.dijkstra_path(self.cycle, 0, 3))
        validate_path(self.cycle, 0, 4, 3, nx.dijkstra_path(self.cycle, 0, 4))

        assert_equal(
            nx.single_source_dijkstra(self.cycle, 0, 0), ({0: 0}, {0: [0]})) 

def bellman_ford_path(G, source, target, weight='weight'):
    """Returns the shortest path from source to target in a weighted graph G.

    Parameters
    ----------
    G : NetworkX graph

    source : node
       Starting node

    target : node
       Ending node

    weight: string, optional (default='weight')
       Edge data key corresponding to the edge weight

    Returns
    -------
    path : list
       List of nodes in a shortest path.

    Raises
    ------
    NetworkXNoPath
       If no path exists between source and target.

    Examples
    --------
    >>> G=nx.path_graph(5)
    >>> print(nx.bellman_ford_path(G, 0, 4))
    [0, 1, 2, 3, 4]

    Notes
    -----
    Edge weight attributes must be numerical.
    Distances are calculated as sums of weighted edges traversed.

    See Also
    --------
    dijkstra_path(), bellman_ford_path_length()
    """
    length, path = single_source_bellman_ford(G, source,
                                              target=target, weight=weight)
    return path 

def test_dijkstra(self):
        (D, P) = nx.single_source_dijkstra(self.XG, 's')
        validate_path(self.XG, 's', 'v', 9, P['v'])
        assert_equal(D['v'], 9)

        validate_path(
            self.XG, 's', 'v', 9, nx.single_source_dijkstra_path(self.XG, 's')['v'])
        assert_equal(dict(
            nx.single_source_dijkstra_path_length(self.XG, 's'))['v'], 9)

        validate_path(
            self.XG, 's', 'v', 9, nx.single_source_dijkstra(self.XG, 's')[1]['v'])
        validate_path(
            self.MXG, 's', 'v', 9, nx.single_source_dijkstra_path(self.MXG, 's')['v'])

        GG = self.XG.to_undirected()
        # make sure we get lower weight
        # to_undirected might choose either edge with weight 2 or weight 3
        GG['u']['x']['weight'] = 2
        (D, P) = nx.single_source_dijkstra(GG, 's')
        validate_path(GG, 's', 'v', 8, P['v'])
        assert_equal(D['v'], 8)     # uses lower weight of 2 on u<->x edge
        validate_path(GG, 's', 'v', 8, nx.dijkstra_path(GG, 's', 'v'))
        assert_equal(nx.dijkstra_path_length(GG, 's', 'v'), 8)

        validate_path(self.XG2, 1, 3, 4, nx.dijkstra_path(self.XG2, 1, 3))
        validate_path(self.XG3, 0, 3, 15, nx.dijkstra_path(self.XG3, 0, 3))
        assert_equal(nx.dijkstra_path_length(self.XG3, 0, 3), 15)
        validate_path(self.XG4, 0, 2, 4, nx.dijkstra_path(self.XG4, 0, 2))
        assert_equal(nx.dijkstra_path_length(self.XG4, 0, 2), 4)
        validate_path(self.MXG4, 0, 2, 4, nx.dijkstra_path(self.MXG4, 0, 2))
        validate_path(
            self.G, 's', 'v', 2, nx.single_source_dijkstra(self.G, 's', 'v')[1])
        validate_path(
            self.G, 's', 'v', 2, nx.single_source_dijkstra(self.G, 's')[1]['v'])

        validate_path(self.G, 's', 'v', 2, nx.dijkstra_path(self.G, 's', 'v'))
        assert_equal(nx.dijkstra_path_length(self.G, 's', 'v'), 2)

        # NetworkXError: node s not reachable from moon
        assert_raises(nx.NetworkXNoPath, nx.dijkstra_path, self.G, 's', 'moon')
        assert_raises(
            nx.NetworkXNoPath, nx.dijkstra_path_length, self.G, 's', 'moon')

        validate_path(self.cycle, 0, 3, 3, nx.dijkstra_path(self.cycle, 0, 3))
        validate_path(self.cycle, 0, 4, 3, nx.dijkstra_path(self.cycle, 0, 4))

        assert_equal(nx.single_source_dijkstra(self.cycle, 0, 0), (0, [0])) 

def dijkstra_path(G, source, target, weight='weight'):
    """Returns the shortest path from source to target in a weighted graph G.

    Parameters
    ----------
    G : NetworkX graph

    source : node
       Starting node

    target : node
       Ending node

    weight: string, optional (default='weight')
       Edge data key corresponding to the edge weight

    Returns
    -------
    path : list
       List of nodes in a shortest path.

    Raises
    ------
    NetworkXNoPath
       If no path exists between source and target.

    Examples
    --------
    >>> G=nx.path_graph(5)
    >>> print(nx.dijkstra_path(G,0,4))
    [0, 1, 2, 3, 4]

    Notes
    -----
    Edge weight attributes must be numerical.
    Distances are calculated as sums of weighted edges traversed.

    See Also
    --------
    bidirectional_dijkstra()
    """
    (length, path) = single_source_dijkstra(G, source, target=target,
                                            weight=weight)
    try:
        return path[target]
    except KeyError:
        raise nx.NetworkXNoPath(
            "node %s not reachable from %s" % (source, target))