Merge pull request #245 from gdsfactory/support-reducing-nodes-in-plo…

…t-nets

Support reducing nodes in plot nets

gplugins/klayout/plot_nets.py

@@ -1,4 +1,6 @@
 import itertools
+from collections.abc import Collection
+from itertools import combinations
 from pathlib import Path
 
 import klayout.db as kdb
@@ -79,6 +81,7 @@ def plot_nets(
     interactive: bool = False,
     include_labels: bool = True,
     only_most_complex: bool = False,
+    nodes_to_reduce: Collection[str] | None = None,
 ) -> None:
     """Plots the connectivity between the components in the KLayout LayoutToNetlist file from :func:`~get_l2n`.
 
@@ -91,13 +94,16 @@ def plot_nets(
         include_labels: Whether to include labels in the graph connected to corresponding cells.
         only_most_complex: Whether to plot only the circuit with most connections or not.
             Helpful for not plotting subcircuits separately.
+        nodes_to_reduce: Nodes to reduce to a single edge. Comparison made with Python ``in`` operator.
+            Helpful for reducing trivial waveguide elements.
     """
+
     match Path(filepath).suffix:
         case ".l2n" | ".txt":
             l2n = kdb.LayoutToNetlist()
             l2n.read(str(filepath))
             netlist = l2n.netlist()
-        case ".spi" | ".spice":
+        case ".cir" | ".sp" | ".spi" | ".spice":
             reader = kdb.NetlistSpiceReader(NoCommentReader())
             netlist = kdb.Netlist()
             netlist.read(str(filepath), reader)
@@ -115,6 +121,25 @@ def plot_nets(
         only_most_complex=only_most_complex,
     )
 
+    if nodes_to_reduce:
+
+        def _removal_condition(node: str, degree: int) -> bool:
+            return degree == 2 and any(e in node for e in nodes_to_reduce)
+
+        while any(
+            _removal_condition(node, degree) for node, degree in G_connectivity.degree
+        ):
+            G_connectivity_tmp = G_connectivity.copy()
+            for node, degree in G_connectivity.degree:
+                if _removal_condition(node, degree):
+                    connected_to_node = [e[1] for e in G_connectivity.edges(node)]
+                    node_pairs_to_connect = list(combinations(connected_to_node, r=2))
+                    for pair in node_pairs_to_connect:
+                        G_connectivity_tmp.add_edge(pair[0], pair[1])
+                    G_connectivity_tmp.remove_node(node)
+                    break
+            G_connectivity = G_connectivity_tmp
+
     # Plotting the graph
     if interactive:
         try:

gplugins/klayout/tests/test_plot_nets.py

@@ -36,15 +36,24 @@ def spice_netlist(tmpdir_factory) -> str:
 @pytest.mark.parametrize("interactive", [True, False])
 @pytest.mark.parametrize("include_labels", [True, False])
 @pytest.mark.parametrize("only_most_complex", [True, False])
+@pytest.mark.parametrize(
+    "nodes_to_reduce", [None, {"straight"}, {"straight", "bend_euler"}]
+)
 def test_plot_nets(
-    klayout_netlist, fully_connected, interactive, include_labels, only_most_complex
+    klayout_netlist,
+    fully_connected,
+    interactive,
+    include_labels,
+    only_most_complex,
+    nodes_to_reduce,
 ):
     plot_nets(
         klayout_netlist,
         fully_connected=fully_connected,
         interactive=interactive,
         include_labels=include_labels,
         only_most_complex=only_most_complex,
+        nodes_to_reduce=nodes_to_reduce,
     )
     if interactive:
         assert Path("connectivity.html").exists()