Use character from node ID as label

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1

Question

Is there a way to use part of the node ID in label?

In the example below, I’d like to use the last character. The
alternative solution would remove the prefix x.

MWE

digraph x {
  node [shape="square"]
  x0
  x1
  x2
  x3
  x4
  x5
  x6
  x7
}

Have

Have

Want

Want

Notes

Simply removing the prefix x in the node name is not a solution for more complex graphs.

I was thinking there might be some syntax that can be combined with \N (e.g., \N[-1]).

2

Does this x5 [label=5] not work for you - i.e. generate each node’s label explicitly?

If not, no there is nothing in the Graphviz language similar to what you want.
However, the following gvpr (https://www.graphviz.org/pdf/gvpr.1.pdf) one-liner will strip the all alpha characters off each node name & assign the result to the node label. More string manipulation is available. (Note, gvpr uses ksh/bash pattern-matching syntax!)

gvpr -c 'N{$.label=sub($.name,"+([a-zA-Z])");}' myfile.gv >myfileNew.gv

Giving:

	graph [rankdir=LR];
	node [label=""];
	edge [style=invis];
	subgraph subset {
		node [shape=none];
		s0	[label=0,
			shape=square];
		s1	[label=1];
		s0 -> s1;
		s3	[label=3,
			shape=square];
		s4	[label=4];
		s3 -> s4;
		s5	[label=5,
			shape=square];
		s6	[label=6,
			shape=square];
		s5 -> s6;
		s7	[label=7];
		s6 -> s7;
		s2	[label=2];
		s1 -> s2;
		s2 -> s3;
		s4 -> s5;
	}
	subgraph fullset {
		node [shape=square];
		fs0	[label=0];
		fs1	[label=1];
		fs0 -> fs1;
		fs2	[label=2];
		fs1 -> fs2;
		fs3	[label=3];
		fs2 -> fs3;
		fs4	[label=4];
		fs3 -> fs4;
		fs5	[label=5];
		fs4 -> fs5;
		fs6	[label=6];
		fs5 -> fs6;
		fs7	[label=7];
		fs6 -> fs7;
	}
}

Note that directly manipulating a label value containing escape-string characters is more work. The Graphviz parsers do not show expanded escape-chars until very late in the game - see:

dot -Tdot myfile.gv

note that \N is not shown expanded