Python networkx.all_simple_paths() Examples

def materialize(self, X, prng, node):
        if self._dgraph.root.id == node.id:
            return X, None

        paths = [path for path in nx.all_simple_paths(self._dgraph.graph, self._dgraph.root.id, node.id)]

        assert len(paths) == 1

        path = paths[0]

        for i in range(len(path)):
            node = self._dgraph.id_node_map[path[i]]

            if util.contains_superclass(node.operator.__class__, 'SplitByPartition'):
                id_node_map = self._dgraph.id_node_map

                Xs = node.operator.transform(X)
                X = Xs[node.idx]
            else:
                X = node.operator.transform(X)
     
        return X, path 

def get_path_iter(graph, source, target, path_length, loop):
    """Return a generator of paths with path_length cutoff from source to
    target."""
    path_iter = nx.all_simple_paths(graph, source, target, path_length)
    try:
        for p in path_iter:
            path = deepcopy(p)
            # Remove common target from a path.
            path.remove(target)
            if loop:
                path.append(path[0])
            # A path should contain at least one edge
            if len(path) < 2:
                continue
            yield path
    except nx.NetworkXNoPath:
        pass 

def test_all_simple_paths_cutoff():
    G = nx.complete_graph(4)
    paths = nx.all_simple_paths(G, 0, 1, cutoff=1)
    assert_equal(set(tuple(p) for p in paths), {(0, 1)})
    paths = nx.all_simple_paths(G, 0, 1, cutoff=2)
    assert_equal(set(tuple(p) for p in paths), {(0, 1), (0, 2, 1), (0, 3, 1)}) 

def test_cutoff_zero():
    G = nx.complete_graph(4)
    paths = nx.all_simple_paths(G, 0, 3, cutoff=0)
    assert_equal(list(list(p) for p in paths), [])
    paths = nx.all_simple_paths(nx.MultiGraph(G), 0, 3, cutoff=0)
    assert_equal(list(list(p) for p in paths), []) 

def test_all_simple_paths_corner_cases():
    assert_equal(list(nx.all_simple_paths(nx.empty_graph(2), 0, 0)), [])
    assert_equal(list(nx.all_simple_paths(nx.empty_graph(2), 0, 1)), [])
    assert_equal(list(nx.all_simple_paths(nx.path_graph(9), 0, 8, 0)), []) 

def test_all_simple_paths_multigraph():
    G = nx.MultiGraph([(1, 2), (1, 2)])
    paths = nx.all_simple_paths(G, 1, 2)
    assert_equal(set(tuple(p) for p in paths), {(1, 2), (1, 2)}) 

def test_all_simple_paths_multigraph_with_cutoff():
    G = nx.MultiGraph([(1, 2), (1, 2), (1, 10), (10, 2)])
    paths = nx.all_simple_paths(G, 1, 2, cutoff=1)
    assert_equal(set(tuple(p) for p in paths), {(1, 2), (1, 2)}) 

def test_all_simple_paths_directed():
    G = nx.DiGraph()
    nx.add_path(G, [1, 2, 3])
    nx.add_path(G, [3, 2, 1])
    paths = nx.all_simple_paths(G, 1, 3)
    assert_equal(set(tuple(p) for p in paths), {(1, 2, 3)}) 

def hamiltonian_path(G, source):
    source = arbitrary_element(G)
    neighbors = set(G[source]) - set([source])
    n = len(G)
    for target in neighbors:
        for path in nx.all_simple_paths(G, source, target):
            if len(path) == n:
                yield path 

def test_cutoff_zero():
    G = nx.complete_graph(4)
    paths = nx.all_simple_paths(G, 0, 3, cutoff=0)
    assert_equal(list(list(p) for p in paths), [])
    paths = nx.all_simple_paths(nx.MultiGraph(G), 0, 3, cutoff=0)
    assert_equal(list(list(p) for p in paths), []) 

def test_source_missing():
    G = nx.Graph()
    nx.add_path(G, [1, 2, 3])
    paths = list(nx.all_simple_paths(nx.MultiGraph(G), 0, 3)) 

def test_target_missing():
    G = nx.Graph()
    nx.add_path(G, [1, 2, 3])
    paths = list(nx.all_simple_paths(nx.MultiGraph(G), 1, 4))

# Tests for shortest_simple_paths 

def test_shortest_simple_paths():
    G = cnlti(nx.grid_2d_graph(4, 4), first_label=1, ordering="sorted")
    paths = nx.shortest_simple_paths(G, 1, 12)
    assert_equal(next(paths), [1, 2, 3, 4, 8, 12])
    assert_equal(next(paths), [1, 5, 6, 7, 8, 12])
    assert_equal([len(path) for path in nx.shortest_simple_paths(G, 1, 12)],
                 sorted([len(path) for path in nx.all_simple_paths(G, 1, 12)])) 

def test_all_simple_paths_cutoff():
    G = nx.complete_graph(4)
    paths = nx.all_simple_paths(G, 0, 1, cutoff=1)
    assert_equal(set(tuple(p) for p in paths), {(0, 1)})
    paths = nx.all_simple_paths(G, 0, 1, cutoff=2)
    assert_equal(set(tuple(p) for p in paths), {(0, 1), (0, 2, 1), (0, 3, 1)}) 

def test_all_simple_paths_multigraph_with_cutoff():
    G = nx.MultiGraph([(1, 2), (1, 2), (1, 10), (10, 2)])
    paths = list(nx.all_simple_paths(G, 1, 2, cutoff=1))
    assert_equal(len(paths), 2)
    assert_equal(set(tuple(p) for p in paths), {(1, 2), (1, 2)}) 

def test_all_simple_paths_multigraph():
    G = nx.MultiGraph([(1, 2), (1, 2)])
    paths = nx.all_simple_paths(G, 1, 1)
    assert_equal(paths, [])
    nx.add_path(G, [3, 1, 10, 2])
    paths = list(nx.all_simple_paths(G, 1, 2))
    assert_equal(len(paths), 3)
    assert_equal(set(tuple(p) for p in paths), {(1, 2), (1, 2), (1, 10, 2)}) 

def test_all_simple_paths_directed():
    G = nx.DiGraph()
    nx.add_path(G, [1, 2, 3])
    nx.add_path(G, [3, 2, 1])
    paths = nx.all_simple_paths(G, 1, 3)
    assert_equal(set(tuple(p) for p in paths), {(1, 2, 3)}) 

def test_all_simple_paths_source_target():
    G = nx.path_graph(4)
    paths = nx.all_simple_paths(G, 1, 1)
    assert_equal(paths, []) 

def test_all_simple_paths_with_two_targets_inside_cycle_emits_two_paths():
    G = nx.cycle_graph(3, create_using=nx.DiGraph())
    G.add_edge(1, 3)
    paths = nx.all_simple_paths(G, 0, [2, 3])
    assert_equal(set(tuple(p) for p in paths), {(0, 1, 2), (0, 1, 3)}) 

def test_all_simple_paths_ignores_cycle():
    G = nx.cycle_graph(3, create_using=nx.DiGraph())
    G.add_edge(1, 3)
    paths = nx.all_simple_paths(G, 0, 3)
    assert_equal(set(tuple(p) for p in paths), {(0, 1, 3)}) 

def test_all_simple_paths_with_two_targets_in_line_emits_two_paths():
    G = nx.path_graph(4)
    paths = nx.all_simple_paths(G, 0, [2, 3])
    assert_equal(set(tuple(p) for p in paths), {(0, 1, 2), (0, 1, 2, 3)}) 

def test_all_simple_paths_with_two_targets_cutoff():
    G = nx.path_graph(4)
    G.add_edge(2, 4)
    paths = nx.all_simple_paths(G, 0, [3, 4], cutoff=3)
    assert_equal(set(tuple(p) for p in paths), {(0, 1, 2, 3), (0, 1, 2, 4)}) 

def test_digraph_all_simple_paths_with_two_targets_emits_two_paths():
    G = nx.path_graph(4, create_using=nx.DiGraph())
    G.add_edge(2, 4)
    paths = nx.all_simple_paths(G, 0, [3, 4])
    assert_equal(set(tuple(p) for p in paths), {(0, 1, 2, 3), (0, 1, 2, 4)}) 

def test_all_simple_paths_with_two_targets_emits_two_paths():
    G = nx.path_graph(4)
    G.add_edge(2, 4)
    paths = nx.all_simple_paths(G, 0, [3, 4])
    assert_equal(set(tuple(p) for p in paths), {(0, 1, 2, 3), (0, 1, 2, 4)}) 

def test_all_simple_paths():
    G = nx.path_graph(4)
    paths = nx.all_simple_paths(G, 0, 3)
    assert_equal(set(tuple(p) for p in paths), {(0, 1, 2, 3)}) 

def root_to_leaf_paths(G):
    """Yields root-to-leaf paths in a directed acyclic graph.

    `G` must be a directed acyclic graph. If not, the behavior of this
    function is undefined. A "root" in this graph is a node of in-degree
    zero and a "leaf" a node of out-degree zero.

    When invoked, this function iterates over each path from any root to
    any leaf. A path is a list of nodes.

    """
    roots = (v for v, d in G.in_degree() if d == 0)
    leaves = (v for v, d in G.out_degree() if d == 0)
    all_paths = partial(nx.all_simple_paths, G)
    # TODO In Python 3, this would be better as `yield from ...`.
    return chaini(starmap(all_paths, product(roots, leaves))) 

def test_shortest_simple_paths():
    G = cnlti(nx.grid_2d_graph(4, 4), first_label=1, ordering="sorted")
    paths = nx.shortest_simple_paths(G, 1, 12)
    assert_equal(next(paths), [1, 2, 3, 4, 8, 12])
    assert_equal(next(paths), [1, 5, 6, 7, 8, 12])
    assert_equal([len(path) for path in nx.shortest_simple_paths(G, 1, 12)],
                 sorted([len(path) for path in nx.all_simple_paths(G, 1, 12)])) 

def test_target_missing():
    G = nx.Graph()
    G.add_path([1,2,3])
    paths = list(nx.all_simple_paths(nx.MultiGraph(G),1,4))

# Tests for shortest_simple_paths 

def test_source_missing():
    G = nx.Graph()
    G.add_path([1,2,3])
    paths = list(nx.all_simple_paths(nx.MultiGraph(G),0,3)) 

def test_cutoff_zero():
    G = nx.complete_graph(4)
    paths = nx.all_simple_paths(G,0,3,cutoff=0)
    assert_equal(list(list(p) for p in paths),[])
    paths = nx.all_simple_paths(nx.MultiGraph(G),0,3,cutoff=0)
    assert_equal(list(list(p) for p in paths),[])