Making public the combinationSet in Combinatorics.

datumbox-framework-core/src/main/java/com/datumbox/framework/core/mathematics/discrete/Combinatorics.java

@@ -19,27 +19,27 @@
 
 /**
  * Utility class for combinations and permutations.
- * 
+ *
  * @author Vasilis Vryniotis <bbriniotis@datumbox.com>
  */
 public class Combinatorics {
-    
+
     /**
      * Returns the permutations of a collection. 
      * Ported from:
      * http://stackoverflow.com/questions/10503392/java-code-for-permutations-of-a-list-of-numbers
-     * 
+     *
      * @param <T>
      * @param elements
-     * @return 
+     * @return
      */
     public static <T> Collection<List<T>> permutations(Collection<T> elements) {
         Collection<List<T>> result = new ArrayList<>();
         if (elements.isEmpty()) {
             result.add(new LinkedList<>());
             return result;
         }
-        
+
         List<T> rest = new LinkedList<>(elements);
         T head = rest.remove(0);
         for (List<T> permutations : permutations(rest)) {
@@ -54,40 +54,48 @@ public static <T> Collection<List<T>> permutations(Collection<T> elements) {
         }
         return result;
     }
-    
+
     /**
      * Returns all the possible combinations of a list. 
      * Ported from:
      * http://codereview.stackexchange.com/questions/26854/recursive-method-to-return-a-set-of-all-combinations
-     * 
+     *
      * @param <T>
      * @param elements
      * @param elementCount
-     * @return 
+     * @return
      */
     public static <T> Collection<List<T>> combinations(List<T> elements, int elementCount) {
-        Set<Set<T>> combinations = getCombinationsFor(elements, elementCount);
-        
+        Set<Set<T>> combinations = combinationsSet(elements, elementCount);
+
         Collection<List<T>> result = new ArrayList<>();
         for(Set<T> linkedset : combinations) {
             result.add(new ArrayList<>(linkedset));
         }
-        
+
         return result;
     }
-
-    private static <T> Set<Set<T>> getCombinationsFor(List<T> group, int subsetSize) {
+
+    /**
+     * Similar to combinations() method it returns all possible combinations in a set.
+     *
+     * @param group
+     * @param subsetSize
+     * @param <T>
+     * @return
+     */
+    public static <T> Set<Set<T>> combinationsSet(List<T> group, int subsetSize) {
         Set<Set<T>> resultingCombinations = new LinkedHashSet<> ();
         int totalSize=group.size();
         if (subsetSize == 0) {
             resultingCombinations.add(new LinkedHashSet<>());
-        } 
+        }
         else if (subsetSize <= totalSize) {
             List<T> remainingElements = new ArrayList<> (group);
             T X = remainingElements.remove(remainingElements.size()-1);
 
-            Set<Set<T>> combinationsExclusiveX = getCombinationsFor(remainingElements, subsetSize);
-            Set<Set<T>> combinationsInclusiveX = getCombinationsFor(remainingElements, subsetSize-1);
+            Set<Set<T>> combinationsExclusiveX = combinationsSet(remainingElements, subsetSize);
+            Set<Set<T>> combinationsInclusiveX = combinationsSet(remainingElements, subsetSize-1);
             for (Set<T> combination : combinationsInclusiveX) {
                 combination.add(X);
             }