buckets.java

来自「一个一元曲线多项式数值演示例子」· Java 代码 · 共 110 行

package numbercruncher.randomutils;

import numbercruncher.mathutils.*;

/**
 * Counters of random values that fall within each interval.
 */
public class Buckets {
  private static final int MAX_BAR_SIZE = 50;

  private AlignRight ar = new AlignRight();

  /** number of intervals */
  private int n;
  /** counters per interval */
  private int counters[];

  /** minimum random value */
  private float rMin;
  /** maximum random value */
  private float rMax;
  /** from min to max */
  private float width;

  /**
   * Constructor.
   * @param n the number of intervals
   */
  public Buckets(int n) {
    this.n = n;
    this.counters = new int[n];
    clear();
  }

  /**
   * Return the counter value for interval i.
   * @param i the value of i
   * @return the counter value
   */
  public int get(int i) {
    return counters[i];
  }

  /**
   * Set the minimum and maximum random values.
   * @param rMin the minimum value
   * @param rMax the maximum value
   */
  public void setLimits(float rMin, float rMax) {
    this.rMin = rMin;
    this.rMax = rMax;
    this.width = (rMax - rMin) / n;
  }

  /**
   * Determine a random value's interval and count it.
   * @param r the random value
   */
  public void put(float r) {
    // Ignore the value if it's out of range.
    if ( (r < rMin) || (r > rMax)) {
      return;
    }

    // Determine its interval and count it.
    int i = (int) ( (r - rMin) / width);
    ++counters[i];
  }

  /**
   * Clear all the interval counters.
   */
  public void clear() {
    for (int i = 0; i < counters.length; ++i) {
      counters[i] = 0;
    }
  }

  /**
   * Print the counter values as a horizontal bar chart. Scale the
   * chart so that the longest bar is MAX_BAR_SIZE.
   */
  public void print() {
    // Get the longest bar's length.
    int maxCount = 0;
    for (int i = 0; i < n; ++i) {
      maxCount = Math.max(maxCount, counters[i]);
    }

    // Compute the scaling factor.
    float factor = ( (float) MAX_BAR_SIZE) / maxCount;

    // Loop to print each bar.
    for (int i = 0; i < n; ++i) {
      int b = counters[i];

      // Interval number.
      ar.print(i, 2);
      ar.print(b, 7);
      System.out.print(": ");

      // Bar.
      int length = Math.round(factor * b);
      for (int j = 0; j < length; ++j) {
        System.out.print("*");
      }
      System.out.println();
    }
  }
}