networkx - 如何在導出的 Graphviz 中顯示邊緣標簽

Question

問題

請告知如何在 Graphviz 中顯示邊緣標簽。

背景

嘗試在 NetworkX 生成的 Graphviz 中顯示邊緣標簽。

在 NetworkX 中，它顯示邊緣標簽。

import matplotlib.pyplot as plt
import networkx as nx

MDG = nx.MultiDiGraph()

# --------------------------------------------------------------------------------
# Forward edges
# --------------------------------------------------------------------------------
forward_edges = [
    ("sushi/0", "goes/1"), 
    ("sushi/0", "with/2"), 
    ("sushi/0", "wasabi/3"), 
    ("goes/1", "with/2"),
    ("goes/1", "wasabi/3"),
    ("with/2", "wasabi/3"),
]
MDG.add_edges_from(
    forward_edges,
    edge_color='b',
    weight='length',
    length=100,
)

# layout definition must come after adding all nodes/edges. 
# Otherwise Node X has no position error.
pos=nx.spring_layout(MDG,seed=5, weight='length')
fig, ax = plt.subplots(figsize=(10, 5))

# --------------------------------------------------------------------------------
# Draw nodes & labels
# --------------------------------------------------------------------------------
nx.draw_networkx_nodes(
    MDG, 
    pos, 
    ax=ax,
    node_size=500,
    node_color="cyan",
)
nx.draw_networkx_labels(
    MDG, 
    pos, 
    ax=ax,
    font_weight='bold',
    font_size=12,
)

# --------------------------------------------------------------------------------
# Draw forward edges
# --------------------------------------------------------------------------------
nx.draw_networkx_edges(
    MDG, 
    pos, 
    ax=ax, 
    edgelist=forward_edges, 
    edge_color="b",
    arrowsize=20,
    arrowstyle="->",
    connectionstyle='arc3, rad=0.1',
)
nx.draw_networkx_edge_labels(
    MDG, 
    pos,
    label_pos=0.2,
    edge_labels={
        ("sushi/0", "goes/1"): 0.3, 
        ("sushi/0", "with/2"): 0.1, 
        ("sushi/0", "wasabi/3"): 0.6, 
        ("goes/1", "with/2"): 0.75,
        ("goes/1", "wasabi/3"): 0.75,
        ("with/2", "wasabi/3"): 0.75,
    },
    font_color='b'
)
nx.set_edge_attributes(
    G=MDG,
    values={
        ("sushi/0", "goes/1", 0.1): {"label": 0.1},
        ("sushi/0", "with/2", 0.1): {"label": 0.2},
        ("sushi/0", "wasabi/3", 0.6): {"label": 0.6},
        ("goes/1", "with/2", 0.1): {"label": 0.1},
        ("goes/1", "wasabi/3", 0.75): {"label": 0.75},
        ("with/2", "wasabi/3", 0.75): {"label": 0.75},
    }
)

但是，Graphviz 沒有顯示它們。

D = nx.drawing.nx_agraph.to_agraph(MDG)

# Modify node fillcolor and edge color.
D.node_attr.update(color='blue', style='filled', fillcolor='yellow')
D.edge_attr.update(color='blue', arrowsize=1)
D.layout('dot')
D.draw('MDG.png')

Answer 1

您沒有將標簽值正確傳遞到邊緣：

nx.set_edge_attributes(
MDG,
values={
    ("sushi/0", "goes/1",0): 0.1,
    ("sushi/0", "with/2",0):0.2,
    ("sushi/0", "wasabi/3",0) :0.6,
    ("goes/1", "with/2",0): 0.1,
    ("goes/1", "wasabi/3",0):0.75,
    ("with/2", "wasabi/3",0):0.75,
},
name = "label"
)

您需要將值作為字典傳遞，鍵為(start_node, end_node, edge_key) 。 由於您使用的是 MultiDiGraph，因此每條邊都有一個鍵，可以使其與具有相同開始和結束節點的其他邊區分開來。

您可以檢查邊緣鍵：

for e in MDG.edges(keys=True):
    print(e)

因為在您的情況下，每個節點對沒有多個邊，所有鍵都為零。

生成 pygrphviz 產生：