toDot method

String toDot({ Map<String, String>? graphAttributes, String vertexLabel(V vertex)?, Map<String, String> vertexAttributes(V vertex)?, String edgeLabel(Edge<V, E> edge)?, Map<String, String> edgeAttributes(Edge<V, E> edge)?, })

Export this graph to DOT Language typically used to describe Graphviz graphs.

Nodes and edges are labelled with their standard print-string, unless a custom vertexLabel or edgeLabel callback is provided.

The display of vertices can be customized by providing vertexAttributes as described in Node Attributes. Similarly edges can be customized by providing edgeAttributes as described in Edge Attributes.

Implementation

String toDot({
  Map<String, String>? graphAttributes,
  String Function(V vertex)? vertexLabel,
  Map<String, String> Function(V vertex)? vertexAttributes,
  String Function(Edge<V, E> edge)? edgeLabel,
  Map<String, String> Function(Edge<V, E> edge)? edgeAttributes,
}) {
  final buffer = StringBuffer();
  buffer.writeln('${isDirected ? 'digraph' : 'graph'} {');
  for (final attribute in _encodeAttributes(graphAttributes ?? {})) {
    buffer.writeln('  $attribute;');
  }
  final ids = vertexStrategy.createMap<int>();
  for (final vertex in vertices) {
    buffer.write('  ${ids[vertex] = ids.length}');
    buffer.write(
      _encodeNodeEdgeAttributes({
        'label': vertexLabel?.call(vertex) ?? vertex.toString(),
        if (vertexAttributes != null) ...vertexAttributes(vertex),
      }),
    );
    buffer.writeln(';');
  }
  final arrow = isDirected ? '->' : '--';
  for (final edge in edges.unique()) {
    buffer.write('  ${ids[edge.source]} $arrow ${ids[edge.target]}');
    buffer.write(
      _encodeNodeEdgeAttributes({
        'label': edgeLabel?.call(edge) ?? edge.value?.toString() ?? '',
        if (edgeAttributes != null) ...edgeAttributes(edge),
      }),
    );
    buffer.writeln(';');
  }
  buffer.write('}');
  return buffer.toString();
}