public class FeaturePenaltyCostFunction
extends Object
implements CostFunction<Spot,Spot>

A cost function that tempers a square distance cost by difference in feature values.

This cost is calculated as follow:

• The distance between the two spots D is calculated
• For each feature in the map, a penalty p is calculated as p = 3 × α × |f1-f2| / (f1+f2), where α is the factor associated to the feature in the map. This expression is such that:
  • there is no penalty if the 2 feature values f1 and f2 are the same;
  • that, with a factor of 1, the penalty if 1 is one value is the double of the other;
  • the penalty is 2 if one is 5 times the other one.
• All penalties are summed, to form P = (1 + ∑ p )
• The cost is set to the square of the product: C = ( D × P )²

For instance: if 2 spots differ by twice the value in a feature which is in the penalty map with a factor of 1, they will look as if they were twice as far.