/// <summary>
/// Is Dominated
/// </summary>
public bool IsDominated(ObjectiveItem <T> other)
{
if (ReferenceEquals(this, other))
{
return(false);
}
else if (null == other)
{
return(false);
}
else if (!ReferenceEquals(Owner, other.Owner))
{
return(false);
}
foreach (var description in Owner.ObjectiveDescriptions)
{
double v1 = this.ObjectiveValue(description);
double v2 = other.ObjectiveValue(description);
if (v2 > v1 && description.Goal == ObjectiveGoal.Min)
{
return(false);
}
if (v2 < v1 && description.Goal == ObjectiveGoal.Max)
{
return(false);
}
}
return(true);
}
/// <summary>
/// Standard Constructor
/// </summary>
/// <param name="solutions">Solutions</param>
/// <param name="objectives">Objectives</param>
public ObjectivesScope(IEnumerable <T> solutions, IEnumerable <ObjectiveDescription <T> > objectives)
{
if (null == solutions)
{
throw new ArgumentNullException(nameof(solutions));
}
else if (null == objectives)
{
throw new ArgumentNullException(nameof(objectives));
}
m_ObjectiveDescriptions = new List <ObjectiveDescription <T> >(objectives);
foreach (var solution in solutions)
{
if (null == solution)
{
continue;
}
ObjectiveItem <T> item = new ObjectiveItem <T>(this, solution);
m_Items.Add(item);
}
}
public int Compare(ObjectiveItem <T> x, ObjectiveItem <T> y)
{
if (ReferenceEquals(x, y))
{
return(0);
}
else if (null == x)
{
return(-1);
}
else if (null == y)
{
return(+1);
}
if (!ReferenceEquals(x.Owner, y.Owner))
{
return(0);
}
int result = x.FrontierLevel.CompareTo(y.FrontierLevel);
if (result < 0)
{
return(1);
}
else if (result > 0)
{
return(-1);
}
result = x.CrowdingDistance.CompareTo(y.CrowdingDistance);
if (result != 0)
{
return(result);
}
return(0);
}
/// <summary>
/// Dominance:
/// +1: left dominates right
/// 0: left and right are not comparable
/// -1: right dominates left
/// </summary>
public static int Dominance(ObjectiveItem <T> left, ObjectiveItem <T> right)
{
if (ReferenceEquals(left, right))
{
return(0);
}
else if (null == left)
{
return(-1);
}
else if (null == right)
{
return(1);
}
else if (!ReferenceEquals(left.Owner, right.Owner))
{
return(0);
}
bool canBeBetter = true;
bool canBeWorse = true;
foreach (var description in left.Owner.ObjectiveDescriptions)
{
double v1 = left.ObjectiveValue(description);
double v2 = right.ObjectiveValue(description);
if (v1 > v2 && description.Goal == ObjectiveGoal.Min)
{
canBeBetter = false;
}
else if (v1 < v2 && description.Goal == ObjectiveGoal.Max)
{
canBeBetter = false;
}
if (v2 > v1 && description.Goal == ObjectiveGoal.Min)
{
canBeWorse = false;
}
else if (v2 < v1 && description.Goal == ObjectiveGoal.Max)
{
canBeWorse = false;
}
if (!canBeBetter && !canBeWorse)
{
return(0);
}
}
if (canBeBetter)
{
return(1);
}
else if (canBeWorse)
{
return(-1);
}
return(0);
}
internal void CoreUpdate()
{
if (m_IsUpdated)
{
return;
}
m_IsUpdated = true;
// dominance
for (int i = 0; i < m_Items.Count; ++i)
{
for (int j = i + 1; j < m_Items.Count; ++j)
{
ObjectiveItem <T> left = m_Items[i];
ObjectiveItem <T> right = m_Items[j];
int d = ObjectiveItem <T> .Dominance(left, right);
if (d > 0)
{
left.m_BetterThan.Add(right);
right.m_WorseThan.Add(left);
}
else if (d < 0)
{
right.m_BetterThan.Add(left);
left.m_WorseThan.Add(right);
}
}
}
// frontiers
HashSet <ObjectiveItem <T> > agenda = new HashSet <ObjectiveItem <T> >(m_Items);
HashSet <ObjectiveItem <T> > skips = new HashSet <ObjectiveItem <T> >();
int level = 0;
while (agenda.Any())
{
level += 1;
List <ObjectiveItem <T> > exclude = new List <ObjectiveItem <T> >(m_Items.Count);
foreach (var item in agenda)
{
if (item.WorseThan.All(x => skips.Contains(x)))
{
exclude.Add(item);
item.m_FrontierLevel = level;
}
}
m_Frontiers.Add(level, exclude);
agenda.ExceptWith(exclude);
skips.UnionWith(exclude);
}
}
