Android Open Source - dice-probabilities Abstract Distribution

From Project

Back to project page dice-probabilities.

License

The source code is released under:

MIT License

If you think the Android project dice-probabilities listed in this page is inappropriate, such as containing malicious code/tools or violating the copyright, please email info at java2s dot com, thanks.

Java Source Code

package org.kleemann.diceprobabilities.distribution;
/* w ww  .  java 2s  . c o  m*/
import org.apache.commons.math3.fraction.BigFraction;

/**
 * <p>
 * A helper class to implement some common Distribution routines
 */
abstract class AbstractDistribution implements Distribution {

  protected AbstractDistribution() {
  }

  @Override
  public BigFraction getProbability(int x) {
    if (x < lowerBound() || x >= upperBound()) {
      return BigFraction.ZERO;
    } else {
      return getProbabilityBounded(x);
    }
  }

  /**
   * <p>
   * Guaranteed not to be called outside the range of lowerBound() and
   * upperBound()-1
   * 
   * <p>
   * A derived class must either implement getProbability(x) or
   * getProbabilityBounded(x)
   */
  protected BigFraction getProbabilityBounded(int x) {
    return null;
  }

  /**
   * <p>
   * A simple default implementation. Takes O(n) with a large constant time.
   */
  @Override
  public BigFraction getCumulativeProbability(int x) {
    BigFraction sum = BigFraction.ZERO;
    x = Math.max(x, lowerBound()); // no need to add up a bunch of zeros
    for (; x < upperBound(); ++x) {
      sum = sum.add(getProbability(x));
    }
    return sum;
  }

  /**
   * <p>
   * If the implementing class has a getCumulativeProbability(x) that performs
   * O(1) then it should override this method to return <code>this</code>
   */
  @Override
  public Distribution cacheCumulative() {
    return new CachedCumulativeDistribution(this);
  }

  @Override
  public boolean isZero() {
    return lowerBound() == 0 && upperBound() == 1
        && getProbability(0).equals(BigFraction.ONE);
  }
}

Java Source Code List