Island model strategy

global.json

@@ -1,5 +1,5 @@
 {
     "sdk": {
-        "version": "6.0.400"
+        "version": "8"
     }
-}
+} 

src/GeneticSharp.Domain/OperatorsStrategy/IslandModelStrategy.cs

@@ -0,0 +1,85 @@
+using System.Collections.Generic;
+using System.Linq;
+
+namespace GeneticSharp
+{
+    public class IslandModelStrategy : OperatorsStrategyBase
+    {
+        private double _migrationProbability; // Probability of a chromosome migrating to another island
+        private int _islandCount; // Number of islands (subpopulations)
+        private Dictionary<IChromosome, int> _islandMapping = new Dictionary<IChromosome, int>(); // Tracks which island each chromosome belongs to
+
+        public IslandModelStrategy(int islandCount, double migrationProbability = 0.1)
+        {
+            _islandCount = islandCount;
+            _migrationProbability = migrationProbability;
+        }
+
+        public override IList<IChromosome> Cross(IPopulation population, ICrossover crossover, float crossoverProbability, IList<IChromosome> parents)
+        {
+            // Asignar islas a los cromosomas si no tienen una
+            int i = 0;
+            foreach (var p in parents)
+            {
+                if (!_islandMapping.ContainsKey(p))
+                {
+                    _islandMapping[p] = (RandomizationProvider.Current.GetDouble() < _migrationProbability)
+                        ? RandomizationProvider.Current.GetInt(0, _islandCount) // Migrar a una isla aleatoria
+                        : i++ % _islandCount; // Asignar de manera cíclica
+                }
+            }
+
+            // Migrar cromosomas a otras islas
+            foreach (var c in parents)
+            {
+                if(RandomizationProvider.Current.GetDouble() < _migrationProbability)
+                    _islandMapping[c] = RandomizationProvider.Current.GetInt(0, _islandCount);
+            }
+
+            var offspring = new List<IChromosome>();
+
+            // Agrupar padres por isla y hacer crossover dentro de cada isla
+            foreach (var island in parents.GroupBy(r => _islandMapping[r]))
+            {
+                var islandParents = island.OrderBy(r => RandomizationProvider.Current.GetDouble()).ToList();
+
+                // Verificar si hay suficientes padres para hacer cruces
+                if (islandParents.Count < crossover.ParentsNumber)
+                {
+                    continue; // O podrías duplicar padres para completar el grupo
+                }
+
+                // Hacer cruces
+                for (int j = 0; j <= islandParents.Count - crossover.ParentsNumber; j += crossover.ParentsNumber)
+                {
+                    var children = SelectParentsAndCross(population, crossover, crossoverProbability, islandParents, j);
+                    if (children != null)
+                    {
+                        // Asignar hijos a la misma isla de sus padres
+                        foreach (var c in children)
+                            _islandMapping[c] = island.Key;
+                        offspring.AddRange(children);
+                    }
+                }
+            }
+
+            // Borrar los elementos de islandMapping que ya no están en la población
+            var allChromosomes = new HashSet<IChromosome>(parents.Concat(offspring).Concat(population.CurrentGeneration.Chromosomes));
+            var toDelete = _islandMapping.Keys.Except(allChromosomes).ToList();
+            foreach (var c in toDelete)
+                _islandMapping.Remove(c);
+
+            return offspring;
+        }
+
+
+        public override void Mutate(IMutation mutation, float mutationProbability, IList<IChromosome> chromosomes)
+        {
+            // Apply mutation to each chromosome individually
+            foreach (var c in chromosomes)
+            {
+                mutation.Mutate(c, mutationProbability);
+            }
+        }
+    }
+}

src/GeneticSharp.Domain/Selections/TournamentSelection.cs

@@ -85,7 +85,7 @@ protected override IList<IChromosome> PerformSelectChromosomes(int number, Gener
             var candidates = generation.Chromosomes.ToList();
             var selected = new List<IChromosome>();
 
-            while (selected.Count < number)
+            while (selected.Count < number && Size <= candidates.Count)
             {
                 var randomIndexes = RandomizationProvider.Current.GetUniqueInts(Size, 0, candidates.Count);
                 var tournamentWinner = candidates.Where((c, i) => randomIndexes.Contains(i)).OrderByDescending(c => c.Fitness).First();
@@ -98,7 +98,14 @@ protected override IList<IChromosome> PerformSelectChromosomes(int number, Gener
                 }
             }
 
-            return selected;
+            while(selected.Count < number && candidates.Any())
+            {
+                var canditate = candidates.First().Clone();
+				selected.Add(canditate);
+				candidates.Remove(canditate);
+			}
+
+			return selected;
         }        
     }
 }