Add branch node, i/o number and more options to SFG digraph

Closes #207 (closed)

b_asic/signal_flow_graph.py

@@ -1376,17 +1376,32 @@ class SFG(AbstractOperation):
         results[key] = value
         return value
 
-    def sfg_digraph(self, show_id=False, engine=None) -> Digraph:
+    def sfg_digraph(
+        self,
+        show_id: bool = False,
+        engine: str = None,
+        branch_node: bool = False,
+        port_numbering: bool = True,
+        splines: str = "spline",
+    ) -> Digraph:
         """
-        Returns a Digraph of the SFG. Can be directly displayed in IPython.
+        Returns a Digraph of the SFG.
+
+        Can be directly displayed in IPython.
 
         Parameters
         ----------
-        show_id : Boolean, optional
-            If True, the graph_id:s of signals are shown. The default is False.
+        show_id : bool, default: False
+            If True, the graph_id:s of signals are shown.
         engine : string, optional
             Graphviz layout engine to be used, see https://graphviz.org/documentation/.
             Most common are "dot" and "neato". Default is None leading to dot.
+        branch_node : bool, default: False
+            Add a branch node in case the fan-out of a signal is two or more.
+        port_numbering : bool, default: True
+            Show the port number in case the number of ports (input or output) is two or more.
+        splines : {"spline", "line", "ortho", "polyline", "curved"}, default: "spline"
+            Spline style, see https://graphviz.org/docs/attrs/splines/ for more info.
 
         Returns
         -------
@@ -1395,23 +1410,56 @@ class SFG(AbstractOperation):
 
         """
         dg = Digraph()
-        dg.attr(rankdir="LR")
+        dg.attr(rankdir="LR", splines=splines)
+        branch_nodes = set()
         if engine is not None:
             dg.engine = engine
         for op in self._components_by_id.values():
             if isinstance(op, Signal):
                 source = cast(OutputPort, op.source)
                 destination = cast(InputPort, op.destination)
-                if show_id:
-                    dg.edge(
-                        source.operation.graph_id,
-                        destination.operation.graph_id,
-                        label=op.graph_id,
+                source_name = (
+                    source.name
+                    if branch_node and source.signal_count > 1
+                    else source.operation.graph_id
+                )
+                label = op.graph_id if show_id else None
+                taillabel = (
+                    str(source.index)
+                    if source.operation.output_count > 1
+                    and (not branch_node or source.signal_count == 1)
+                    and port_numbering
+                    else None
+                )
+                headlabel = (
+                    str(destination.index)
+                    if destination.operation.input_count > 1 and port_numbering
+                    else None
+                )
+                dg.edge(
+                    source_name,
+                    destination.operation.graph_id,
+                    label=label,
+                    taillabel=taillabel,
+                    headlabel=headlabel,
+                )
+                if (
+                    branch_node
+                    and source.signal_count > 1
+                    and source_name not in branch_nodes
+                ):
+                    branch_nodes.add(source_name)
+                    dg.node(source_name, shape='point')
+                    taillabel = (
+                        str(source.index)
+                        if source.operation.output_count > 1 and port_numbering
+                        else None
                     )
-                else:
                     dg.edge(
                         source.operation.graph_id,
-                        destination.operation.graph_id,
+                        source_name,
+                        arrowhead='none',
+                        taillabel=taillabel,
                     )
             else:
                 dg.node(op.graph_id, shape=_OPERATION_SHAPE[op.type_name()])