Class Histogram

src/java/org/apache/nutch/util/Histogram.java:21–129

import java.util.*;

public class Histogram<E> {

  private Map<E, HistogramEntry> map = new HashMap<E, HistogramEntry>();
  private float totalValue = 0;
  private int totalCount = 0;

  public void add(E x) {
    add(x, 1);
  }

  public void add(E x, float value) {
    HistogramEntry entry;
    if (map.containsKey(x)) {
      entry = map.get(x);
      entry.value += value;
      entry.count++;
    } else {
      entry = new HistogramEntry();
      entry.value = value;
      entry.count = 1;
      map.put(x, entry);
    }
    totalValue += value;
    totalCount += 1;
  }

  public Set<E> getKeys() {
    return map.keySet();
  }

  public float getValue(E x) {
    return map.get(x).value;
  }

  public int getCount(E x) {
    return map.get(x).count;
  }

  public void add(Histogram<E> other) {
    for (E x : other.getKeys()) {
      add(x, other.getValue(x));
    }
  }

  public Histogram<E> normalize() {
    Histogram<E> normalized = new Histogram<E>();
    Set<E> keys = getKeys();
    for (E x : keys) {
      normalized.add(x, getValue(x) / totalValue);
    }
    return normalized;
  }

  public List<E> sortInverseByValue() {
    List<Map.Entry<E, HistogramEntry>> list = new Vector<Map.Entry<E, HistogramEntry>>(
        map.entrySet());

    // Sort the list using an annonymous inner class implementing Comparator for