content: package edu.berkeley.nlp.lm.collections;
  
  import java.io.Serializable;
  import java.text.NumberFormat;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.Random;
  import java.util.Set;
  import java.util.TreeSet;
  
  /**
   * A map from objects to doubles. Includes convenience methods for getting,
   * setting, and incrementing element counts. Objects not in the counter will
   * return a count of zero. The counter is backed by a HashMap .(unless specified
   * otherwise with the MapFactory constructor).
   * 
   * @author lots of people
   */
  public class Counter<E> implements Serializable
  {
  	private static final long serialVersionUID = 1L;
  
  	private final Map<E, Double> entries;
  
  	private boolean dirty = true;
  
  	private double cacheTotal = 0.0;
  
  	private double defaultCount = 0.0;
  
  	public double getDefaultCount() {
  		return defaultCount;
  	}
  
  	public void setDefaultCount(final double deflt) {
  		this.defaultCount = deflt;
  	}
  
  	/**
  	 * The elements in the counter.
  	 * 
  	 * @return set of keys
  	 */
  	public Set<E> keySet() {
  		return entries.keySet();
  	}
  
  	public Set<Entry<E, Double>> entrySet() {
  		return entries.entrySet();
  	}
  
  	/**
  	 * The number of entries in the counter (not the total count -- use
  	 * totalCount() instead).
  	 */
  	public int size() {
  		return entries.size();
  	}
  
  	/**
  	 * True if there are no entries in the counter (false does not mean
  	 * totalCount > 0)
  	 */
  	public boolean isEmpty() {
  		return size() == 0;
  	}
  
  	/**
  	 * Returns whether the counter contains the given key. Note that this is the
  	 * way to distinguish keys which are in the counter with count zero, and
  	 * those which are not in the counter (and will therefore return count zero
  	 * from getCount().
  	 * 
  	 * @param key
  	 * @return whether the counter contains the key
  	 */
  	public boolean containsKey(final E key) {
  		return entries.containsKey(key);
  	}
  
  	/**
  	 * Get the count of the element, or zero if the element is not in the
  	 * counter.
  	 * 
  	 * @param key
  	 * @return
  	 */
  	public double getCount(final E key) {
  		final Double value = entries.get(key);
  		if (value == null) return defaultCount;
  		return value;
  	}
  
  	/**
  	 * I know, I know, this should be wrapped in a Distribution class, but it's
  	 * such a common use...why not. Returns the MLE prob. Assumes all the counts
  	 * are >= 0.0 and totalCount > 0.0. If the latter is false, return 0.0 (i.e.
  	 * 0/0 == 0)
  	 * 
  	 * @author Aria
  	 * @param key
  	 * @return MLE prob of the key
  	 */
  	public double getProbability(final E key) {
  		final double count = getCount(key);
  		final double total = totalCount();
  		if (total < 0.0) { throw new RuntimeException("Can't call getProbability() with totalCount < 0.0"); }
  		return total > 0.0 ? count / total : 0.0;
  	}
  
  	/**
  	 * Destructively normalize this Counter in place.
  	 */
  	public void normalize() {
  		final double totalCount = totalCount();
  		for (final E key : keySet()) {
  			setCount(key, getCount(key) / totalCount);
  		}
  		dirty = true;
  	}
  
  	/**
  	 * Set the count for the given key, clobbering any previous count.
  	 * 
  	 * @param key
  	 * @param count
  	 */
  	public void setCount(final E key, final double count) {
  		entries.put(key, count);
  		dirty = true;
  	}
  
  	/**
  	 * Set the count for the given key if it is larger than the previous one;
  	 * 
  	 * @param key
  	 * @param count
  	 */
  	public void put(final E key, final double count, final boolean keepHigher) {
  		if (keepHigher && entries.containsKey(key)) {
  			final double oldCount = entries.get(key);
  			if (count > oldCount) {
  				entries.put(key, count);
  			}
  		} else {
  			entries.put(key, count);
  		}
  		dirty = true;
  	}
  
  	/**
  	 * Will return a sample from the counter, will throw exception if any of the
  	 * counts are < 0.0 or if the totalCount() <= 0.0
  	 * 
  	 * @return
  	 * 
  	 * @author aria42
  	 */
  	public E sample(final Random rand) {
  		final double total = totalCount();
  		if (total <= 0.0) { throw new RuntimeException(String.format("Attempting to sample() with totalCount() %.3f\n", total)); }
  		double sum = 0.0;
  		final double r = rand.nextDouble();
  		for (final Map.Entry<E, Double> entry : entries.entrySet()) {
  			final double count = entry.getValue();
  			final double frac = count / total;
  			sum += frac;
  			if (r < sum) { return entry.getKey(); }
  		}
  		throw new IllegalStateException("Shoudl've have returned a sample by now....");
  	}
  
  	/**
  	 * Will return a sample from the counter, will throw exception if any of the
  	 * counts are < 0.0 or if the totalCount() <= 0.0
  	 * 
  	 * @return
  	 * 
  	 * @author aria42
  	 */
  	public E sample() {
  		return sample(new Random());
  	}
  
  	public void removeKey(final E key) {
  		setCount(key, 0.0);
  		dirty = true;
  		removeKeyFromEntries(key);
  	}
  
  	/**
  	 * @param key
  	 */
  	protected void removeKeyFromEntries(final E key) {
  		entries.remove(key);
  	}
  
  	/**
  	 * Set's the key's count to the maximum of the current count and val. Always
  	 * sets to val if key is not yet present.
  	 * 
  	 * @param key
  	 * @param val
  	 */
  	public void setMaxCount(final E key, final double val) {
  		final Double value = entries.get(key);
  		if (value == null || val > value.doubleValue()) {
  			setCount(key, val);
  
  			dirty = true;
  		}
  	}
  
  	/**
  	 * Set's the key's count to the minimum of the current count and val. Always
  	 * sets to val if key is not yet present.
  	 * 
  	 * @param key
  	 * @param val
  	 */
  	public void setMinCount(final E key, final double val) {
  		final Double value = entries.get(key);
  		if (value == null || val < value.doubleValue()) {
  			setCount(key, val);
  
  			dirty = true;
  		}
  	}
  
  	/**
  	 * Increment a key's count by the given amount.
  	 * 
  	 * @param key
  	 * @param increment
  	 */
  	public double incrementCount(final E key, final double increment) {
  		final double newVal = getCount(key) + increment;
  		setCount(key, newVal);
  		dirty = true;
  		return newVal;
  	}
  
  	/**
  	 * Increment each element in a given collection by a given amount.
  	 */
  	public void incrementAll(final Collection<? extends E> collection, final double count) {
  		for (final E key : collection) {
  			incrementCount(key, count);
  		}
  		dirty = true;
  	}
  
  	public <T extends E> void incrementAll(final Counter<T> counter) {
  		incrementAll(counter, 1.0);
  	}
  
  	public <T extends E> void incrementAll(final Counter<T> counter, final double scale) {
  		for (final Entry<T, Double> entry : counter.entrySet()) {
  			incrementCount(entry.getKey(), scale * entry.getValue());
  		}
  		dirty = true;
  	}
  
  	/**
  	 * Finds the total of all counts in the counter. This implementation
  	 * iterates through the entire counter every time this method is called.
  	 * 
  	 * @return the counter's total
  	 */
  	public double totalCount() {
  		if (!dirty) { return cacheTotal; }
  		double total = 0.0;
  		for (final Map.Entry<E, Double> entry : entries.entrySet()) {
  			total += entry.getValue();
  		}
  		cacheTotal = total;
  		dirty = false;
  		return total;
  	}
  
  	public Collection<Entry<E, Double>> getEntriesSortedByIncreasingCount() {
  		final List<Entry<E, Double>> sorted = new ArrayList<Entry<E, Double>>(entrySet());
  		Collections.sort(sorted, new EntryValueComparator(false));
  		return sorted;
  	}
  
  	public Collection<Entry<E, Double>> getEntriesSortedByDecreasingCount() {
  		final List<Entry<E, Double>> sorted = new ArrayList<Entry<E, Double>>(entrySet());
  		Collections.sort(sorted, new EntryValueComparator(true));
  		return sorted;
  	}
  
  	/**
  	 * Finds the key with maximum count. This is a linear operation, and ties
  	 * are broken arbitrarily.
  	 * 
  	 * @return a key with minumum count
  	 */
  	public E argMax() {
  		double maxCount = Double.NEGATIVE_INFINITY;
  		E maxKey = null;
  		for (final Map.Entry<E, Double> entry : entries.entrySet()) {
  			if (entry.getValue() > maxCount || maxKey == null) {
  				maxKey = entry.getKey();
  				maxCount = entry.getValue();
  			}
  		}
  		return maxKey;
  	}
  
  	public double min() {
  		return maxMinHelp(false);
  	}
  
  	public double max() {
  		return maxMinHelp(true);
  	}
  
  	private double maxMinHelp(final boolean max) {
  		double maxCount = max ? Double.NEGATIVE_INFINITY : Double.POSITIVE_INFINITY;
  
  		for (final Map.Entry<E, Double> entry : entries.entrySet()) {
  			if ((max && entry.getValue() > maxCount) || (!max && entry.getValue() < maxCount)) {
  
  				maxCount = entry.getValue();
  			}
  		}
  		return maxCount;
  	}
  
  	/**
  	 * Returns a string representation with the keys ordered by decreasing
  	 * counts.
  	 * 
  	 * @return string representation
  	 */
  	@Override
  	public String toString() {
  		return toStringSortedByKeys();
  	}
  
  	public String toStringSortedByKeys() {
  		final StringBuilder sb = new StringBuilder("[");
  
  		final NumberFormat f = NumberFormat.getInstance();
  		f.setMaximumFractionDigits(5);
  		int numKeysPrinted = 0;
  		for (final E element : new TreeSet<E>(keySet())) {
  
  			sb.append(element.toString());
  			sb.append(" : ");
  			sb.append(f.format(getCount(element)));
  			if (numKeysPrinted < size() - 1) sb.append(", ");
  			numKeysPrinted++;
  		}
  		if (numKeysPrinted < size()) sb.append("...");
  		sb.append("]");
  		return sb.toString();
  	}
  
  	public Counter() {
  
  		entries = new HashMap<E, Double>();
  	}
  
  	public Counter(final Counter<? extends E> counter) {
  		this();
  		incrementAll(counter);
  	}
  
  	public Counter(final Collection<? extends E> collection) {
  		this();
  		incrementAll(collection, 1.0);
  	}
  
  	public void pruneKeysBelowThreshold(final double cutoff) {
  		final Iterator<E> it = entries.keySet().iterator();
  		while (it.hasNext()) {
  			final E key = it.next();
  			final double val = entries.get(key);
  			if (val < cutoff) {
  				it.remove();
  			}
  		}
  		dirty = true;
  	}
  
  	public Set<Map.Entry<E, Double>> getEntrySet() {
  		return entries.entrySet();
  	}
  
  	public boolean isEqualTo(final Counter<E> counter) {
  		boolean tmp = true;
  		final Counter<E> bigger = counter.size() > size() ? counter : this;
  		for (final E e : bigger.keySet()) {
  			tmp &= counter.getCount(e) == getCount(e);
  		}
  		return tmp;
  	}
  
  	public static void main(final String[] args) {
  		final Counter<String> counter = new Counter<String>();
  		System.out.println(counter);
  		counter.incrementCount("planets", 7);
  		System.out.println(counter);
  		counter.incrementCount("planets", 1);
  		System.out.println(counter);
  		counter.setCount("suns", 1);
  		System.out.println(counter);
  		counter.setCount("aliens", 0);
  		System.out.println(counter);
  		System.out.println(counter.toString());
  		System.out.println("Total: " + counter.totalCount());
  	}
  
  	public void clear() {
  		entries.clear();
  		dirty = true;
  	}
  
  	/**
  	 * Sets all counts to the given value, but does not remove any keys
  	 */
  	public void setAllCounts(final double val) {
  		for (final E e : keySet()) {
  			setCount(e, val);
  		}
  
  	}
  
  	public double dotProduct(final Counter<E> other) {
  		double sum = 0.0;
  		for (final Map.Entry<E, Double> entry : getEntrySet()) {
  			final double otherCount = other.getCount(entry.getKey());
  			if (otherCount == 0.0) continue;
  			final double value = entry.getValue();
  			if (value == 0.0) continue;
  			sum += value * otherCount;
  
  		}
  		return sum;
  	}
  
  	public void scale(final double c) {
  
  		for (final Map.Entry<E, Double> entry : getEntrySet()) {
  			entry.setValue(entry.getValue() * c);
  		}
  
  	}
  
  	public Counter<E> scaledClone(final double c) {
  		final Counter<E> newCounter = new Counter<E>();
  
  		for (final Map.Entry<E, Double> entry : getEntrySet()) {
  			newCounter.setCount(entry.getKey(), entry.getValue() * c);
  		}
  
  		return newCounter;
  	}
  
  	public Counter<E> difference(final Counter<E> counter) {
  		final Counter<E> clone = new Counter<E>(this);
  		for (final E key : counter.keySet()) {
  			final double count = counter.getCount(key);
  			clone.incrementCount(key, -1 * count);
  		}
  		return clone;
  	}
  
  	public Counter<E> toLogSpace() {
  		final Counter<E> newCounter = new Counter<E>(this);
  		for (final E key : newCounter.keySet()) {
  			newCounter.setCount(key, Math.log(getCount(key)));
  		}
  		return newCounter;
  	}
  
  	public boolean approxEquals(final Counter<E> other, final double tol) {
  		for (final E key : keySet()) {
  			if (Math.abs(getCount(key) - other.getCount(key)) > tol) {//
  				return false;
  			}
  		}
  		for (final E key : other.keySet()) {
  			if (Math.abs(getCount(key) - other.getCount(key)) > tol) {
  				//
  				return false;
  			}
  		}
  		return true;
  	}
  
  	public void setDirty(final boolean dirty) {
  		this.dirty = dirty;
  	}
  
  	public Iterable<Double> values() {
  		return new Iterable<Double>()
  		{
  
  			@Override
  			public Iterator<Double> iterator() {
  
  				return new Iterator<Double>()
  				{
  					Iterator<Entry<E, Double>> entryIterator = entrySet().iterator();
  
  					@Override
  					public boolean hasNext() {
  						return entryIterator.hasNext();
  					}
  
  					@Override
  					public Double next() {
  						return entryIterator.next().getValue();
  					}
  
  					@Override
  					public void remove() {
  						entryIterator.remove();
  					}
  				};
  			}
  		};
  
  	}
  
  	public void prune(final Set<E> toRemove) {
  		for (final E e : toRemove) {
  			removeKey(e);
  		}
  	}
  
  	public void pruneExcept(final Set<E> toKeep) {
  		final List<E> toRemove = new ArrayList<E>();
  		for (final E key : entries.keySet()) {
  			if (!toKeep.contains(key)) toRemove.add(key);
  		}
  		for (final E e : toRemove) {
  			removeKey(e);
  		}
  	}
  
  	public static <L> Counter<L> absCounts(final Counter<L> counts) {
  		final Counter<L> res = new Counter<L>();
  		for (final Map.Entry<L, Double> entry : counts.entrySet()) {
  			res.incrementCount(entry.getKey(), Math.abs(entry.getValue()));
  		}
  		return res;
  	}
  
  	// Compare by value.
  	public class EntryValueComparator implements Comparator<Entry<E, Double>>
  	{
  
  		/**
  		 * @param descending
  		 */
  		public EntryValueComparator(final boolean descending) {
  			super();
  			this.descending = descending;
  		}
  
  		private final boolean descending;
  
  		@Override
  		public int compare(final Entry<E, Double> e1, final Entry<E, Double> e2) {
  			return descending ? Double.compare(e2.getValue(), e1.getValue()) : Double.compare(e1.getValue(), e2.getValue());
  		}
  	}
  
  	public void putAll(final double d) {
  		for (final Entry<E, Double> entry : entries.entrySet()) {
  
  			setCount(entry.getKey(), d);
  		}
  		dirty = true;
  	}
  
  }
  