public void NormalizeToIndexOrder()

in Chemistry/src/DataModel/LadderOperator/IndexOrderedSequence.cs [63:106]
39 lines of code
8 McCabe index (conditional complexity)

        public void NormalizeToIndexOrder()
        {
            var tmp = new NormalOrderedSequence<TIndex>(this);
            if (!tmp.IsInIndexOrder())
            {
                var left = tmp.Sequence.Select((op, idx) => new { op, idx }).Where(x => x.op.Type == RaisingLowering.u);
                var right = tmp.Sequence.Select((op, idx) => new { op, idx }).Where(x => x.op.Type == RaisingLowering.d);

                var upArrayIndices = tmp.Sequence.Select((op, idx) => new { op, idx }).Where(x => x.op.Type == RaisingLowering.u).Select(x => x.idx).ToArray();
                var downArrayIndices = tmp.Sequence.Select((op, idx) => new { op, idx }).Where(x => x.op.Type == RaisingLowering.d).Select(x => x.idx).ToArray();

                // Bubble sort spin-orbital indices of creation operator.
                while (!tmp.IsInIndexCreationCanonicalOrder())
                {
                    for (int idx = 0; idx < upArrayIndices.Count() - 1; idx++)
                    {
                        if (tmp.Sequence.ElementAt(upArrayIndices.ElementAt(idx)).Index.CompareTo(tmp.Sequence.ElementAt(upArrayIndices.ElementAt(idx + 1)).Index) > 0)
                        {
                            var tmpLadderOperator = tmp.Sequence.ElementAt(upArrayIndices.ElementAt(idx));
                            tmp.Sequence[upArrayIndices.ElementAt(idx)] = tmp.Sequence[upArrayIndices.ElementAt(idx + 1)];
                            tmp.Sequence[upArrayIndices.ElementAt(idx + 1)] = tmpLadderOperator;
                            tmp.Coefficient = -1 * tmp.Coefficient;
                        }
                    }
                }

                // Bubble sort spin-orbital indices of annihilation operator.
                while (!tmp.IsInIndexAnnihilationCanonicalOrder())
                {
                    for (int idx = 0; idx < downArrayIndices.Length - 1; idx++)
                    {
                        if (tmp.Sequence.ElementAt(downArrayIndices.ElementAt(idx)).Index.CompareTo(tmp.Sequence.ElementAt(downArrayIndices.ElementAt(idx + 1)).Index) < 0)
                        {
                            var tmpLadderOperator = tmp.Sequence.ElementAt(downArrayIndices.ElementAt(idx));
                            tmp.Sequence[downArrayIndices.ElementAt(idx)] = tmp.Sequence[downArrayIndices.ElementAt(idx + 1)];
                            tmp.Sequence[downArrayIndices.ElementAt(idx + 1)] = tmpLadderOperator;
                            tmp.Coefficient = -1 * tmp.Coefficient;
                        }
                    }
                }
            }
            Sequence = tmp.Sequence;
            Coefficient = tmp.Coefficient;
        }