我们如何从 GV 文件创建具有非重叠子图的 GV 文件？

Question

图形

我有一个包含 3 个子图的 GV 文件：

1. cluster_1
2. cluster_2
3. cluster_3

   Final_Graph.gv的来源：

   digraph Final_Graph {
       graph [center=true rankdir=LR ratio=compress size="15,10"]
       a
       b
       c
       d
       a -> b [label = 1]
       a -> c [label = 2]
       a -> d [label = 3]
       b -> d [label = 4]
       c -> d [label = 5]
   
       subgraph cluster_1{
           color=lightgrey style=filled
           label="A"
           a
           b
       }
       
       subgraph cluster_2{
           color=lightgrey style=filled
           label="B"
           a
           b
       }
       
       subgraph cluster_3{
           color=lightgrey style=filled
           label="C"
           c
           d
       }
   }
   

   渲染：

   通缉

   我希望创建子图不重叠的其他 GV 文件（即没有相似节点的子图，因此对于这种情况，第一个文件可以有簇 1 和 3，第二个文件可以有簇 2 和 3）。

   代码

   我在 Python 中使用这个函数来完成这个任务：

   import networkx as nx
   import itertools
   def draw_graph_combinations():
   
   # Load the original graph
     G = nx.drawing.nx_agraph.read_dot("Final_Graph.gv")
   
   # Create an empty dictionary to store the subgraphs
     subgraphs = {}
     
   
   # Iterate over the edges of the graph
     for u, v, data in G.edges(data=True):
       label = data.get("label")
       if label not in subgraphs:
           subgraphs[label] = nx.DiGraph()
      
   
     for node in G.nodes:
       # Add the node to each subgraph
       for label, subgraph in subgraphs.items():
           subgraph.add_node(node)
           
     for label, subgraph in subgraphs.items():
       for edge in G.edges:
           subgraph.add_edge(edge[0], edge[1])
   
    # Get all combinations of subgraphs
     combinations = itertools.combinations(subgraphs.items(), len(subgraphs))
   
   # Iterate over the combinations
     for i, subgraph_items in enumerate(combinations):
       combined_subgraph = nx.DiGraph()
       for label, subgraph in subgraph_items:
           combined_subgraph = nx.compose(combined_subgraph, subgraph)
       nx.drawing.nx_agraph.write_dot(combined_subgraph, f"combined_subgraph_{i}.gv")
   

   问题

   但是，当我在 Python 中运行此函数时，打印出的文件仅包含原始文件的节点和边缘，而没有显示子图。

   问题

   Python 中有没有什么方法可以将这个 GV 文件分成子图不重叠的其他文件？

Answer 1

您可以使用包 PyGraphviz 来读取、修改、写入和渲染 Graphviz 图形。

PyGraphviz

先决条件：必须在您的系统上安装 graphviz 二进制文件。 使用 pip 安装 Python 包：

pip install pygraphviz

见Install — PyGraphviz 1.10 documentation。

去除子图

注意：除了从源字符串加载之外，您还可以将文件句柄或文件名作为参数传递给构造函数AGraph(filename='Final_Graph.gv')或AGraph(Final_Graph.gv)。

import pygraphviz as pgv

s = '''digraph Final_Graph {
    graph [center=true rankdir=LR ratio=compress size="15,10"]
    a
    b
    c
    d
    a -> b [label = 1]
    a -> c [label = 2]
    a -> d [label = 3]
    b -> d [label = 4]
    c -> d [label = 5]
    subgraph cluster_1{
        color=lightgrey style=filled
        label="A"
        a
        b
    }
    
    subgraph cluster_2{
        color=lightgrey style=filled
        label="B"
        a
        b
    }
    
    subgraph cluster_3{
        color=lightgrey style=filled
        label="C"
        c
        d
    }
}'''

G = pgv.AGraph(string=s)  # loading a graph from source string
# print some information of the parsed graph 
print(f"Graph '{G.get_name()}' has:")
print(f"* {len(G.nodes())} nodes")
print(f"* {len(G.edges())} edges")
print(f"* {len(G.subgraphs())} subgraphs")

# the first file could have clusters 1 and 3
G_copy1 = G.copy()  # Return a copy of the graph.
G_copy1.remove_subgraph('cluster_2')  # Remove subgraph with given name: cluster 2
print("## Copy 1: without cluster 2
", G_copy1.string())  # Return a string (unicode) representation of graph in dot format.
G_copy1.write('without_cluster_2.dot')  # Write graph in dot format to file on path.

# the second file could have clusters 2 and 3
G_copy2 = G.copy()  # Return a copy of the graph.
G_copy2.remove_subgraph('cluster_1')  # Remove subgraph with given name: cluster 1
print("## Copy 2: without cluster 1
", G_copy1.string())  # Return a string (unicode) representation of graph in dot format.
G_copy2.write('without_cluster_1.dot')  # Write graph in dot format to file on path.

输出：2 个文件，每个文件有 28 行（384 字节）

• without_cluster_1.dot
• without_cluster_2.dot

并在控制台上进行以下操作：

Graph 'Final_Graph' has:
* 4 nodes
* 5 edges
* 3 subgraphs
## Copy 1: without cluster 2
 digraph Final_Graph {
    graph [center=true,
        rankdir=LR,
        ratio=compress,
        size="15,10"
    ];
    subgraph cluster_1 {
        graph [color=lightgrey,
            label=A,
            style=filled
        ];
        a;
        b;
    }
    subgraph cluster_3 {
        graph [color=lightgrey,
            label=C,
            style=filled
        ];
        c;
        d;
    }
    a -> b   [label=1];
    a -> c   [label=2];
    a -> d   [label=3];
    b -> d   [label=4];
    c -> d   [label=5];
}

## Copy 2: without cluster 1
 digraph Final_Graph {
    graph [center=true,
        rankdir=LR,
        ratio=compress,
        size="15,10"
    ];
    subgraph cluster_1 {
        graph [color=lightgrey,
            label=A,
            style=filled
        ];
        a;
        b;
    }
    subgraph cluster_3 {
        graph [color=lightgrey,
            label=C,
            style=filled
        ];
        c;
        d;
    }
    a -> b   [label=1];
    a -> c   [label=2];
    a -> d   [label=3];
    b -> d   [label=4];
    c -> d   [label=5];
}