如何将Graphviz流程图的图例定位在图表左下角？

要将图例子图放到图表左下角，你可以通过强制rank层级和不可见辅助边来实现，以下是修改后的完整代码：

# Graph
  graph [
    overlap = true
    fontsize = 10
  ]
  
  # Define styles for Datasets and Analyses
  node [fontname = 'Calibri Light', fontcolor = white, style = filled]
  
  # Datasets (boxes)
  node [shape = box, fillcolor = firebrick3]  # Set dataset style
  A
  B
  
  # Analyses (circles)
  node [shape = circle, fixedsize = true, width = .9, fillcolor = steelblue3]
  C
  D
  
  # Edges
  {A B}->C
  A->D
  
  # Subgraph for legend
  subgraph cluster_legend {
    graph [
      label = 'Legend'
      labelloc = 't'
      labeljust= 'l'
      fontname = 'Calibri Light'
      color = lightgrey
      rank = sink  # 强制图例子图排在整个图表的最底部
      margin = 10  # 调整子图边距，避免和主图节点太近
    ]
    
    # Global node style
    node [fontsize = 9]
    
    # Legend entry for Analysis
    node [shape = circle, fixedsize = true, fillcolor = steelblue3, width = .5, height = .3]
    legend_analysis [label = 'Analysis']
    
    # Legend entry for Data
    node [shape = box, fillcolor = firebrick3, width = .5, height = .5]
    legend_data [label = 'Data']
    
    # Make legend items horizontal
    {rank = same; legend_data; legend_analysis}
  }

  # 添加不可见边，让图例和左下角的B节点对齐，确保靠左
  B -> legend_data [style = invis]
}

关键修改点说明： #

• rank = sink：将图例子图设置为整个图表的最低层级，确保它位于底部区域
• 不可见边B -> legend_data [style = invis]：强制图例子图和左下角的B节点在水平方向对齐，避免图例偏移到底部中间
• margin = 10：调整图例子图的内边距，优化和主图节点的视觉间距

如果你的图表左下角节点不是B，只需要把不可见边的起点换成对应节点即可。

内容的提问来源于stack exchange，提问作者mat