fix HyperGraph.plot with non-consec nodes (#36)

cotengra/plot.py

@@ -426,7 +426,9 @@ def _edge_colorer(ix):
  if node_color is True:
  from .schematic import auto_colors
 
- node_colors = auto_colors(H.get_num_nodes())
+ node_colors = dict(
+ zip(sorted(H.nodes), auto_colors(H.get_num_nodes()))
+ )
 
  def _node_colorer(nd):
  return node_colors[nd]

tests/test_hypergraph.py

@@ -1,6 +1,7 @@
 import pytest
 import cotengra as ctg
 
+
 def test_shortest_distances():
  inputs, output, _, size_dict = ctg.utils.lattice_equation([3, 3])
  hg = ctg.HyperGraph(inputs, output, size_dict)
@@ -34,6 +35,28 @@ def test_compute_loops():
  hg = ctg.HyperGraph(inputs, output, size_dict)
  loops = list(hg.compute_loops())
  assert set(loops) == {
- (0, 1, 3, 4), (1, 2, 4, 5), (3, 4, 6, 7), (4, 5, 7, 8)
+ (0, 1, 3, 4),
+ (1, 2, 4, 5),
+ (3, 4, 6, 7),
+ (4, 5, 7, 8),
  }
  assert len(list(hg.compute_loops(max_loop_length=6))) == 8
+
+
+def test_plot_nonconsec():
+ import matplotlib as mpl
+
+ mpl.use("Template")
+
+ inputs = [
+ ("a", "b", "x"),
+ ("b", "c", "d"),
+ ("c", "e", "y"),
+ ("e", "a", "d"),
+ ]
+ output = ("x", "y")
+ size_dict = {"x": 2, "y": 3, "a": 4, "b": 5, "c": 6, "d": 7, "e": 8}
+
+ hg = ctg.HyperGraph(inputs, output, size_dict)
+ hg.contract(0, 1)
+ hg.plot()