networkx.algorithms.shortest_paths.astar.astar_path¶

astar_path(G, source, target, heuristic=None, weight='weight')[source]¶

Returns a list of nodes in a shortest path between source and target using the A* (“A-star”) algorithm.

There may be more than one shortest path. This returns only one.

Parameters:

G (NetworkX graph)
source (node) – Starting node for path
target (node) – Ending node for path
heuristic (function) – A function to evaluate the estimate of the distance from the a node to the target. The function takes two nodes arguments and must return a number.
weight (string, optional (default=’weight’)) – Edge data key corresponding to the edge weight.

Raises:

NetworkXNoPath – If no path exists between source and target.

Examples

>>> G = nx.path_graph(5)
>>> print(nx.astar_path(G, 0, 4))
[0, 1, 2, 3, 4]
>>> G = nx.grid_graph(dim=[3, 3])  # nodes are two-tuples (x,y)
>>> nx.set_edge_attributes(G, {e: e[1][0]*2 for e in G.edges()}, 'cost')
>>> def dist(a, b):
...    (x1, y1) = a
...    (x2, y2) = b
...    return ((x1 - x2) ** 2 + (y1 - y2) ** 2) ** 0.5
>>> print(nx.astar_path(G, (0, 0), (2, 2), heuristic=dist, weight='cost'))
[(0, 0), (0, 1), (0, 2), (1, 2), (2, 2)]