From 010ef801d5fbe5b68cf77c1126a96194584c2767 Mon Sep 17 00:00:00 2001
From: Peter Dobsan <pdobsan@gmail.com>
Date: Sun, 24 Sep 2023 23:25:47 +0200
Subject: [PATCH] raise RuntimeError from "canon_graph() if colored

---
 src/pynauty/graph.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/pynauty/graph.py b/src/pynauty/graph.py
index c10fc9e..ccb0f1a 100644
--- a/src/pynauty/graph.py
+++ b/src/pynauty/graph.py
@@ -223,6 +223,8 @@ def canon_graph(g):
     return ->
         new canonical graph.
     '''
+    if g.vertex_coloring:
+        raise RuntimeError("canon_graph() is not implemented for vertex-colored graphs yet.")
     c = certificate(g)
     set_length = len(c) // g.number_of_vertices
     sets = [c[set_length*k:set_length*(k+1)] for k in range(g.number_of_vertices)]