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 or function) – If this is a string, then edge weights will be accessed via the edge attribute with this key (that is, the weight of the edge joining
u
tov
will beG.edges[u, v][weight]
). If no such edge attribute exists, the weight of the edge is assumed to be one. If this is a function, the weight of an edge is the value returned by the function. The function must accept exactly three positional arguments: the two endpoints of an edge and the dictionary of edge attributes for that edge. The function must return a number.
- 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)]
See also
shortest_path()
,dijkstra_path()