Control position of clusters in Graphviz

Question

I have a graphiz project where I would like to position my clusters horizontally from left to right with cluster_c2 (called QGIS) in the middle. I have attempted to use the newrank=true; as described here without success. The current output of my graphviz script is:

My current script is:

digraph {

    node [shape=record, fontname="Arial"];
    rankdir=LR;

    L [label="Line"]
    ML [label="Multi-Line"]
    QL [label="Line"]
    QML [label = "Multi-Line"]
    QCS [label = "Circular-String"]
    QCC [label = "Compound-Curve"]
    P [label="PolyLine"]

    subgraph cluster_c1 {
        label = "SpatiaLite";
        fontname="Arial";
        L;
        ML;
    }

    subgraph cluster_c2 {
        label = "QGIS";
        fontname="Arial";
        QL;
        QML;
        QCS;
        QCC;
    }

    subgraph cluster_c3 {
        label = "Shapefile";
        fontname="Arial";
        P;
    }

    L -> QL   [dir=both];
    QCS -> L [color=grey];
    QCS -> ML   [color=grey];
    QCC -> ML  [color=grey];
    QML -> ML [dir=both];
    QCC -> L [ color=grey];
    QML-> L [color=grey];
    QL -> ML [color=grey];
    QCS -> P;
    QCC -> P;
    QML -> P [dir=both];
    QL -> P ;

}

Answer 1

I don't know how it works, but it seems that combination of newrank="true" and rank=same inside each subgraph works:

digraph {
  node [shape=record, fontname="Arial"];
  newrank=true;
  rankdir=LR;

  L [label="Line"];
  ML [label="Multi-Line"];
  QL [label="Line"];
  QML [label = "Multi-Line"];
  QCS [label = "Circular-String"];
  QCC [label = "Compound-Curve"];
  P [label="PolyLine"];

  subgraph cluster_c1 { 
    rank=same;
    label = "SpatiaLite";
    fontname="Arial";
    L;
    ML;
  }

  subgraph cluster_c2 { 
    rank=same;
    label = "QGIS";
    fontname="Arial";
    QL;
    QML;
    QCS;
    QCC;
  }

  subgraph cluster_c3 { 
    rank=same;
    label = "Shapefile";
    fontname="Arial";
    P;
  }

  L -> QL   [dir=both];   
  ML -> QML [dir=both];        
  QCS -> L [color=grey];
  QCS -> ML   [color=grey];   
  QCC -> ML  [color=grey];   
  QCC -> L [ color=grey];
  QML-> L [color=grey];  
  QL -> ML [color=grey];    
  QCS -> P; 
  QCC -> P; 
  QML -> P [dir=both];
  QL -> P ;
}