/** Population.java - This is an array of individuals.
 */

public class Population
{
  public static final int SIZE = 20;
  public Individual [] individual;
  
  /** default constructor
   */
  public Population()
  {
    individual = new Individual[SIZE];
    for (int i = 0; i < SIZE; ++i)
      individual[i] = new Individual();
  }
  
  /** findAverageFitness - In order for us to observe the overall
   *  health of the population, and thereby see how the genetic algorithm
   *  is progressing through its generations.
   *  I'm calling findFitness() instead of referencing the fitness attribute
   *  just in case the attribute is not up to date.
   */
  public double findAverageFitness()
  {
    double sum = 0.0;
    for (int i = 0; i < SIZE; ++i)
      sum += individual[i].findFitness();
    return sum / SIZE;
  }
  
  /** toString - print each individual on its own line.
   *  Be careful with the syntax.
   */
  public String toString()
  {
    StringBuilder sb = new StringBuilder();
    sb.append(String.format("Population's average fitness is %5.2f\n", 
                            this.findAverageFitness()));
    for (int i = 0; i < SIZE; ++i)
      sb.append(String.format("%s\n", individual[i].toString()));
    return sb.toString();
  }
}