graphviz dot flow chart table-labels place and sometimes truncated

Question

I've created a quite big flow diagram. Some of the edge-labels (rendered as tables) have these problems:

the text in some table cells ends up outside the table cell
the table sometimes crosses the edge
when the flow diagram is rendered as a PNG image (which is my desired output), then some parts of these tables are outside the image area

The idea of this graph is to have a horizontal timeline, with "column nodes" happening at the same time (or close together in the timeline). So to enforce this "time flow" I ended up using rankdir="LR"; along with {rank=same; my_first_node; my_second_node; }.

How do I make those "table labels" a bit better rendered? Like not crossing the edges, having the text completely inside their table cell, seeing the full graph when exporting to PNG?

I generate the PNG output image with this command: dot -Tpng foo.dot -o foo.png, see below the "table label" issues:

digraph my_flow {
  // global graph conf
  rankdir="LR"; // orziontal
  nodesep=0.9;

  // shared conf
  edge [ fontname="Courier New", fontsize=20];
  node [ fontname=Helvetica, fontsize=26, style="rounded,filled", nojustify=true];

  // many different node "classes"
  node[shape=doublecircle, color=navajowhite]
    my_first_node; my_second_node;
  node[shape=rect, color=aquamarine2]
    first_std_horiz_node; second_std_horiz_node;

  // custom configuration for each node
  first_std_horiz_node[label="First \l std \l horizontal \l node"]
  second_std_horiz_node[label="Second \l std \l horizontal \l node"]
  my_first_node[label="My \l first \l node"]
  my_second_node[label="My \l second \l node"]

  // sets of nodes in the same "column"
  {rank=same; my_first_node; my_second_node; }

  first_std_horiz_node -> second_std_horiz_node
  second_std_horiz_node -> my_first_node
  my_first_node -> my_second_node [label=<
                             action type 1
                             action 1 very very very very long description
                             action type 2
                             action X
                             action Y
                             action type 3
                             action A
                             action B
                             action C
                             action type 4
                             action Q
                             action W
                           >];
}

user_976470 · Answer

If you put your table in a node rather than an edge label, things look better; and using the HTML Tag , you can break lines in the table. Editing your code accordingly, I come up with

digraph my_flow {
  // global graph conf
  rankdir="LR"; // horizontal
  nodesep=0.9;

  // shared conf
  node [ fontname=Helvetica, fontsize=26, style="rounded,filled", nojustify=true];

  // node instead of edge label
  my_table[ shape=none, margin=0, fontname="Courier New", fontsize=20, label=<
          
           action type 1
           action 1
very very very very
long description
           action type 2
           action X
           action Y
           action type 3
           action A
           action B
           action C
           action type 4
           action Q
           action W
         > ]

  // many different node "classes"
  node[shape=doublecircle, color=navajowhite]
    my_first_node; my_second_node;
  node[shape=rect, color=aquamarine2]
    first_std_horiz_node; second_std_horiz_node;

  // custom configuration for each node
  first_std_horiz_node[label="First \l std \l horizontal \l node"]
  second_std_horiz_node[label="Second \l std \l horizontal \l node"]
  my_first_node[label="My \l first \l node"]
  my_second_node[label="My \l second \l node"]

  // sets of nodes in the same "column"
  {rank=same; my_first_node; my_table; my_second_node; }

  first_std_horiz_node -> second_std_horiz_node -> my_first_node;
  my_first_node -> my_table[ dir = none ];
  my_table -> my_second_node;
}

which yields

EDIT

After the revisions in the table code, it is also possible to use the table as a label; for easier reference here the full code again:

digraph my_flow {
  // global graph conf
  rankdir="LR"; // horizontal
  nodesep=0.9;

  // shared conf
  node [ fontname=Helvetica, fontsize=26, style="rounded,filled", nojustify=true];

  // node instead of edge label


  // many different node "classes"
  node[shape=doublecircle, color=navajowhite]
    my_first_node; my_second_node;
  node[shape=rect, color=aquamarine2]
    first_std_horiz_node; second_std_horiz_node;

  // custom configuration for each node
  first_std_horiz_node[label="First \l std \l horizontal \l node"]
  second_std_horiz_node[label="Second \l std \l horizontal \l node"]
  my_first_node[label="My \l first \l node"]
  my_second_node[label="My \l second \l node"]

  // sets of nodes in the same "column"
  {rank=same; my_first_node; my_second_node; }

  first_std_horiz_node -> second_std_horiz_node -> my_first_node;
  my_first_node -> my_second_node[ fontname="Courier New", fontsize=20, label=<
          
           action type 1
           action 1
very very very very
long description
           action type 2
           action X
           action Y
           action type 3
           action A
           action B
           action C
           action type 4
           action Q
           action W
         > ];
}

which yields

In the given context I find the node solution preferable / cleaner, as it makes it clearer where the info in the table belongs to. But if there is more to it, the edge way will also work.

graphviz dot flow chart table-labels place and sometimes truncated

1 Answers