Java tutorial
/* * (c) 2005 David B. Bracewell * * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ package com.davidbracewell.math; import com.davidbracewell.collection.Counter; import com.davidbracewell.tuple.Pair; import com.google.common.base.Function; import com.google.common.base.Preconditions; import com.google.common.collect.Iterables; import com.google.common.collect.Lists; import com.google.common.collect.Sets; import com.google.common.primitives.Doubles; import org.apache.mahout.math.list.DoubleArrayList; import org.apache.mahout.math.map.OpenObjectDoubleHashMap; import java.io.Serializable; import java.util.*; /** * The type Compact counter. * * @author David B. Bracewell */ public class CompactCounter<V> implements Serializable, Counter<V> { private static final long serialVersionUID = 6889762694761078118L; private final OpenObjectDoubleHashMap<V> map; private double sum; /** * Create fast counter. * * @param items the items * @return the fast counter */ @SafeVarargs public static <V> CompactCounter<V> create(V... items) { Preconditions.checkNotNull(items); if (items.length == 0) { return new CompactCounter<>(); } return new CompactCounter<>(Arrays.asList(items)); } /** * Create fast counter. * * @param item the item * @param value the value * @return the fast counter */ public static <V> CompactCounter<V> create(V item, double value) { CompactCounter<V> counter = new CompactCounter<>(1); counter.increment(item, value); return counter; } /** * Create fast counter. * * @param items the items * @param values the values * @return the fast counter */ public static <V> CompactCounter<V> create(V[] items, double[] values) { Preconditions.checkNotNull(items); Preconditions.checkNotNull(values); Preconditions.checkArgument(items.length == values.length, "dimensions do not match."); CompactCounter<V> counter = new CompactCounter<>(items.length); for (int i = 0; i < items.length; i++) { counter.increment(items[i], values[i]); } return counter; } /** * Instantiates a new Compact counter. */ public CompactCounter() { this(100); } /** * Instantiates a new Compact counter. * * @param iterable the iterable */ public CompactCounter(Iterable<? extends V> iterable) { this(Iterables.size(Preconditions.checkNotNull(iterable))); incrementAll(Preconditions.checkNotNull(iterable)); } /** * Instantiates a new Fast counter. * * @param map the map */ public CompactCounter(Map<V, ? extends Number> map) { this(Preconditions.checkNotNull(map).size()); for (Map.Entry<V, ? extends Number> e : map.entrySet()) { this.set(e.getKey(), e.getValue().doubleValue()); } } /** * Instantiates a new Compact counter. * * @param initialSize the initial size */ public CompactCounter(int initialSize) { Preconditions.checkArgument(initialSize > 0, "initialize size should be > 0."); this.map = new OpenObjectDoubleHashMap<>(initialSize); } @Override public double get(V item) { return map.get(item); } @Override public void increment(V item) { increment(item, 1d); } @Override public void increment(V item, double amount) { map.adjustOrPutValue(Preconditions.checkNotNull(item), amount, amount); sum += amount; } @Override public void incrementAll(Iterable<? extends V> iterable) { incrementAll(iterable, 1d); } @Override public void incrementAll(Iterable<? extends V> iterable, double amount) { for (V item : Preconditions.checkNotNull(iterable)) { increment(item, amount); } } @Override public void decrementAll(Iterable<? extends V> iterable) { incrementAll(iterable, -1d); } @Override public void decrementAll(Iterable<? extends V> iterable, double amount) { incrementAll(iterable, -amount); } @Override public void decrement(V item) { increment(item, -1); } @Override public void decrement(V item, double amount) { increment(item, -amount); } @Override public Map<V, Double> asMap() { return new AbstractMap<V, Double>() { @Override @SuppressWarnings("unchecked") public Double get(Object key) { return map.get((V) key); } @Override public int size() { return map.size(); } @Override @SuppressWarnings("unchecked") public boolean containsKey(Object key) { return map.containsKey((V) key); } @Override public Set<V> keySet() { return Sets.newHashSet(map.keys()); } @Override public Set<Entry<V, Double>> entrySet() { return new AbstractSet<Entry<V, Double>>() { @Override public Iterator<Entry<V, Double>> iterator() { return new IteratorWrapper(); } @Override public int size() { return map.size(); } }; } }; } private class IteratorWrapper implements Iterator<Map.Entry<V, Double>> { final Iterator<V> keyIterator = CompactCounter.this.iterator(); @Override public boolean hasNext() { return keyIterator.hasNext(); } @Override public Map.Entry<V, Double> next() { if (!keyIterator.hasNext()) { throw new NoSuchElementException(); } V key = keyIterator.next(); return Pair.of(key, map.get(key)); } @Override public void remove() { keyIterator.remove(); } } @Override public boolean isEmpty() { return map.isEmpty(); } @Override public int size() { return map.size(); } @Override public Set<V> items() { return Sets.newHashSet(map.keys()); } @Override public Collection<Double> counts() { return new AbstractList<Double>() { final DoubleArrayList list = map.values(); @Override public Double get(int index) { return list.get(index); } @Override public int size() { return list.size(); } }; } @Override public Counter<V> adjustValues(Function<Double, Double> function) { Preconditions.checkNotNull(function); CompactCounter<V> newCounter = new CompactCounter<>(map.size()); for (V item : map.keys()) { Double out = function.apply(map.get(item)); if (out != null) { newCounter.increment(item, out); } } return newCounter; } @Override public double sum() { return sum; } @Override public double average() { if (map.isEmpty()) { return 0d; } return sum / (double) map.size(); } @Override public double standardDeviation() { if (map.isEmpty()) { return 0d; } return Math.sqrt(Math.abs(sumOfSquares() - average() * sum) / ((double) map.size() - 1)); } @Override public double sumOfSquares() { if (map.isEmpty()) { return 0d; } double sumOfSq = 0d; for (V item : map.keys()) { sumOfSq += Math.pow(map.get(item), 2); } return sumOfSq; } @Override public double magnitude() { return Math.sqrt(sumOfSquares()); } @Override public void merge(Counter<? extends V> other) { merge(other.asMap()); } @Override public void removeZeroCounts() { for (V item : map.keys()) { if (map.get(item) == 0) { map.removeKey(item); } } map.trimToSize(); } @Override public void merge(Map<? extends V, ? extends Number> other) { Preconditions.checkNotNull(other); for (Map.Entry<? extends V, ? extends Number> e : other.entrySet()) { increment(e.getKey(), e.getValue().doubleValue()); } } @Override public List<V> itemsByCount(boolean ascending) { List<V> list = Lists.newArrayList(); map.keysSortedByValue(list); if (!ascending) { Collections.reverse(list); } return list; } @Override public boolean contains(V item) { return map.containsKey(item); } @Override public double maximumCount() { if (map.isEmpty()) { return 0d; } return Doubles.max(map.values().elements()); } @Override public double minimumCount() { if (map.isEmpty()) { return 0d; } return Doubles.min(map.values().elements()); } @Override public void clear() { map.clear(); sum = 0d; } @Override public double remove(V item) { double amt = map.get(item); map.removeKey(item); sum -= amt; return amt; } @Override public void set(V item, double count) { double amt = map.get(item); map.put(item, count); sum -= amt; sum += count; } @Override public void divideBySum() { if (map.isEmpty()) { return; } for (V item : map.keys()) { map.put(item, map.get(item) / sum); } sum = 1d; } @Override public Iterator<V> iterator() { return map.keys().iterator(); } @Override public String toString() { return map.toString(); } }//END OF CompactCounter