如何使用 Python 和 Cypher 在 Apache Age 中实现最短路径算法

正如前面的答案中提到的，在ApacheAge中没有预定义的函数来寻找两个 node 之间的最短路径，但我们可以定义一个实现Dijkstra算法的Python函数来寻找图中 node 之间的最短路径.

以下是Dijkstra算法在Python语言中的实现:

import heapq

def dijkstra(age, start_node, end_node):
    # initialize distances and visited nodes
    distances = {start_node: 0}
    visited = set()
    heap = [(0, start_node)]

    # loop until all nodes are visited or destination node is found
    while heap:
        # get the node with the smallest distance
        (dist, current_node) = heapq.heappop(heap)

        # check if we have found the destination node
        if current_node == end_node:
            path = []
            while current_node in predecessors:
                path.append(current_node)
                current_node = predecessors[current_node]
            path.append(start_node)
            path.reverse()
            return path

        # check if we have already visited this node
        if current_node in visited:
            continue

        # add current node to visited set
        visited.add(current_node)

        # check neighbors of current node
        for neighbor_edge in current_node.get_edges_outgoing():
            neighbor_node = neighbor_edge.get_end_node()
            distance = dist + neighbor_edge.get_property("distance")

            # update distance to neighbor node if it's shorter than previous
            if neighbor_node not in distances or distance < distances[neighbor_node]:
                distances[neighbor_node] = distance
                heapq.heappush(heap, (distance, neighbor_node))

    # no path found
    return None

要使用该函数，可以传入age对象、startnode和end_node对象，它将返回它们之间的最短路径.

例如，要在问题中给出的图中找到纽约和休斯顿之间的最短路径，您可以这样调用函数:

start_node = node_a
end_node = node_d
shortest_path = dijkstra(age, start_node, end_node)
print(shortest_path)