public static Graph GenerateKekuleForm(Graph g, BitArray subset, BitArray aromatic, bool inplace)
{
// make initial (empty) matching - then improve it, first
// by matching the first edges we find, most of time this
// gives us a perfect matching if not we maximise it
// with Edmonds' algorithm
Matching m = Matching.CreateEmpty(g);
int n = BitArrays.Cardinality(subset);
int nMatched = ArbitraryMatching.Initial(g, m, subset);
if (nMatched < n)
{
if (n - nMatched == 2)
{
nMatched = ArbitraryMatching.AugmentOnce(g, m, nMatched, subset);
}
if (nMatched < n)
{
nMatched = MaximumMatching.Maximise(g, m, nMatched, IntSet.FromBitArray(subset));
}
if (nMatched < n)
{
throw new InvalidSmilesException("Could not Kekulise");
}
}
return(inplace ? Assign(g, subset, aromatic, m)
: CopyAndAssign(g, subset, aromatic, m));
}
public void Furan_2()
{
Graph g = Graph.FromSmiles("c1ccoc1");
Matching m = Matching.CreateEmpty(g);
ArbitraryMatching.Initial(g,
m,
AllOf(0, 1, 2, 4));
Assert.AreEqual(1, m.GetMatches().Count());
Assert.IsTrue(Compares.AreOrderLessDeepEqual(
new[] { Tuple.Of(0, 1) },
m.GetMatches()));
}
public void Furan()
{
Graph g = Graph.FromSmiles("o1cccc1");
Matching m = Matching.CreateEmpty(g);
ArbitraryMatching.Initial(g, m,
AllOf(1, 2, 3, 4));
// note this matching is maximum
Assert.AreEqual(2, m.GetMatches().Count());
Assert.IsTrue(Compares.AreOrderLessDeepEqual(
new[] { Tuple.Of(1, 2), Tuple.Of(3, 4) },
m.GetMatches()));
}
public void Benzene()
{
Graph g = Graph.FromSmiles("c1ccccc1");
Matching m = Matching.CreateEmpty(g);
ArbitraryMatching.Initial(g,
m,
AllOf(0, 1, 2, 3, 4, 5));
Assert.AreEqual(3, m.GetMatches().Count());
Assert.IsTrue(Compares.AreOrderLessDeepEqual(
new[] {
Tuple.Of(0, 1),
Tuple.Of(2, 3),
Tuple.Of(4, 5),
},
m.GetMatches()));
}
public static Graph Resonate(Graph g, BitArray cyclic, bool ordered)
{
BitArray subset = new BitArray(g.Order);
for (int u = BitArrays.NextSetBit(cyclic, 0); u >= 0; u = BitArrays.NextSetBit(cyclic, u + 1))
{
// candidates must have a bonded
// valence of one more than their degree
// and in a ring
int uExtra = g.BondedValence(u) - g.Degree(u);
if (uExtra > 0)
{
int other = -1;
Edge target = null;
int d = g.Degree(u);
for (int j = 0; j < d; ++j)
{
Edge e = g.EdgeAt(u, j);
int v = e.Other(u);
// check for bond validity
if (e.Bond.Order == 2)
{
int vExtra = g.BondedValence(v) - g.Degree(v);
if (cyclic[v] && vExtra > 0)
{
if (HasAdjDirectionalLabels(g, e, cyclic) && !InSmallRing(g, e))
{
other = -1;
break;
}
if (vExtra > 1 && HasAdditionalCyclicDoubleBond(g, cyclic, u, v))
{
other = -1;
break;
}
if (other == -1)
{
other = v; // first one
target = e;
}
else
{
other = -2; // found more than one
}
}
// only one double bond don't check any more
if (uExtra == 1)
{
break;
}
}
}
if (other >= 0)
{
subset.Set(u, true);
subset.Set(other, true);
target.SetBond(Bond.Implicit);
}
}
}
if (!ordered)
{
g = g.Sort(new Graph.CanOrderFirst());
}
Matching m = Matching.CreateEmpty(g);
int n = BitArrays.Cardinality(subset);
int nMatched = ArbitraryMatching.Dfs(g, m, subset);
if (nMatched < n)
{
if (n - nMatched == 2)
{
nMatched = ArbitraryMatching.AugmentOnce(g, m, nMatched, subset);
}
if (nMatched < n)
{
nMatched = MaximumMatching.Maximise(g, m, nMatched, IntSet.FromBitArray(subset));
}
if (nMatched < n)
{
throw new ApplicationException("Could not Kekulise");
}
}
// assign new double bonds
for (int v = BitArrays.NextSetBit(subset, 0); v >= 0; v = BitArrays.NextSetBit(subset, v + 1))
{
int w = m.Other(v);
subset.Set(w, false);
g.CreateEdge(v, w).SetBond(Bond.Double);
}
return(g);
}
