How to change the size of edge in dot (graphviz)? I would like to make some edges "bolded".
I wanted to supplement shuvalov's answer. penwidth is indeed the correct command. Additionally, in shuvalov's answer penwidth is both a node and an edge property--also correct.
The distinction i wanted to make:
penwidth, when used as a node property (e.g., "NodeA" [penwidth = 5]) affects the border line weight for that node
penwidth, when used as a edge property affects the line weight of the edge (default value is "1", specifying penwidth=2 will make the edge appear in bold type
if you want to change the line weight of an edge, you do not need to change penwidth for the two nodes connected by that edge (as shuvalev's answer might suggest)
for a directed graph (the edges have a direction) you might also wish to change the size/weight of the arrowhead and arrowtail, along with the edge weight, so that all three remain proportional
the length of an edge can be changed by setting the weight property, as elsewhere, the default value is 1.0; increasing that value increases the cost of stretching this edge during rendering (i.e., the drawing algorithm applies a higher penalty to solutions in which this edge is longer); notice that the edge from 1 to 4 is shorter than the edge from 1 to 2.
The following code should illustrate all of this. The rendered graph is shown below the code.
digraph {
/* declare the node & style them */
"Node 1" [shape=diamond, penwidth=3, style=filled, fillcolor="#FCD975"];
"Node 2" [style=filled,fillcolor="#9ACEEB" ];
"Node 3" [shape=diamond, style=filled, fillcolor="#FCD975" ];
"Node 4" [style=filled, fillcolor="#9ACEEB" ]
/* declare the edges & style them */
"Node 1" -> "Node 2" [dir=none, weight=1, penwidth=3] ;
"Node 1" -> "Node 3" [dir=none, color="#9ACEEB"] ;
"Node 1" -> "Node 4" [arrowsize=.5, weight=2.]
}