Automatic multiline labels in Graphviz?

Question

I'm using Graphviz to draw some graphs. I'm using labels on nodes and I can put in "\n" to force it to split the label across 2 lines. Is there some way to get Graphviz (or dot which I'm using) to automatically see that it should split some nodes labels, and for it itself to make the best choice automagically?

Answer 1

I've also searched for this, but I don't think it's possible in the current version. The current "solution" is to write code that automatically adds the "\n" every few characters, based on the minimum distance between nodes (nodesep attribute, if I'm not mistaken).

Answer 2

Yes, HTML-like labels (<...>) support
tag, using which you can break the lines. E.g.

"A" -> "B"
[label = <1. <br/>
 2. <br/>
 3. <br/>
 4. <br/>
 .... <br/> 
> color="blue" style="dashed"];

These also work when embedding Graphviz in LaTeX, where \n would not.

Answer 3

(Not sure how we're supposed to deal with duplicate questions?)

dot2tex (latex + graphviz) handles text wrapping, along with other workarounds to the typesetting limitations of graphviz. You'll find a short example at this duplicate question, with prescribed fixed line width.

Answer 4

One person wrote a Perl script to achieve this. I found it in his blog: Text wrapping with dot (graphviz).

Perl script:

#!/usr/bin/perl
use strict;
 
my $usage = "setdotlabelwidth [char-width] < [dotfile]";
my $width = shift() or die("Usage: $usage $!");
 
while(<STDIN>)
{
  if(m/label="(.*?)"/)
  {
    my $labeltext = $1;
    my @words = split(/ /, $labeltext);
    my @newtext = ();
    my $newline = "";
    foreach my $word(@words)
    {
      if( length($newline) > 0 and
          length($newline) + length($word) > $width )
      {
        push(@newtext, $newline);
        $newline = "";
      }
      $newline .= " " if( length($newline) > 0 );
      $newline .= $word;
    }
    push(@newtext, $newline) if( length($newline) > 0 );
    my $newlabel = join("\\n", @newtext);
    s/label=".*?"/label="$newlabel"/;
  }
  print;
}

Save this program as setdotlabelwidth, then simply pipe the output into GraphViz. If for example you want to set the width to 35 characters, then the command is:

./setdotlabelwidth 35 < tile-error-correction.dot | dot -Tpng -o tile-error-correction.png

Before: After: