code: public List<Type> cvSet(int folds, Random rand)
      {
          double[] splits = new double[folds];
          Arrays.fill(splits, 1.0/folds);
          return randomSplit(rand, splits);
      }
docs: Creates <tt>folds</tt> data sets that contain data from this data set.
  The data points in each set will be random. These are meant for cross
  validation
  
  @param folds the number of cross validation sets to create. Should be greater then 1
  @param rand the source of randomness
  @return the list of data sets.