为什么我的来自 a.gv 文件的叶节点之间的距离矩阵会导致一个空字典？

Question

How to get a distance matrix between leaf nodes from a.gv file? I'm trying to obtain the shortest distance between leaves in an unweighted graph.

I have tried this:

def compute_distance_matrix(graph):
    leaf_nodes = [node for node in graph.nodes() if graph.degree(node) == 1]
    leaf_labels = [node.split('s')[1] for node in leaf_nodes]
    distance_matrix = {}
    for i, node1 in enumerate(leaf_nodes):
        for j, node2 in enumerate(leaf_nodes[i+1:], i+1):
            if nx.has_path(graph, node1, node2):
                distance = nx.shortest_path_length(graph, node1, node2)
                distance_matrix[(leaf_labels[i], leaf_labels[j])] = distance
            elif graph.has_edge(node1, node2):
                distance_matrix[(leaf_labels[i], leaf_labels[j])] = 1
    return distance_matrix

but it returns an empty dict.

Answer 1

def compute_distance_matrix(nw):
    tree = Tree(nw)
    leaves = tree.get_leaves()
    leaf_labels = [leaf.name for leaf in leaves]
    distance_matrix = {}
    for i, node1 in enumerate(leaves):
        for j, node2 in enumerate(leaves[i+1:], i+1):
            distance = node1.get_distance(node2)
            distance_matrix[(leaf_labels[i], leaf_labels[j])] = distance
    return distance_matrix