/**
* 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 org.apache.mahout.common;
import org.apache.hadoop.io.BinaryComparable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.WritableComparator;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.Serializable;
import java.util.Arrays;
/**
* A {@link WritableComparable} which encapsulates an ordered pair of signed integers.
*/
public final class IntPairWritable extends BinaryComparable
implements WritableComparable<BinaryComparable>, Serializable, Cloneable {
static final int INT_BYTE_LENGTH = 4;
static final int INT_PAIR_BYTE_LENGTH = 2 * INT_BYTE_LENGTH;
private byte[] b = new byte[INT_PAIR_BYTE_LENGTH];
public IntPairWritable() {
setFirst(0);
setSecond(0);
}
public IntPairWritable(IntPairWritable pair) {
b = Arrays.copyOf(pair.getBytes(), INT_PAIR_BYTE_LENGTH);
}
public IntPairWritable(int x, int y) {
putInt(x, b, 0);
putInt(y, b, INT_BYTE_LENGTH);
}
public void set(int x, int y) {
putInt(x, b, 0);
putInt(y, b, INT_BYTE_LENGTH);
}
public void setFirst(int x) {
putInt(x, b, 0);
}
public int getFirst() {
return getInt(b, 0);
}
public void setSecond(int y) {
putInt(y, b, INT_BYTE_LENGTH);
}
public int getSecond() {
return getInt(b, INT_BYTE_LENGTH);
}
@Override
public void readFields(DataInput in) throws IOException {
in.readFully(b);
}
@Override
public void write(DataOutput out) throws IOException {
out.write(b);
}
@Override
public int hashCode() {
return Arrays.hashCode(b);
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (!super.equals(obj)) {
return false;
}
if (!(obj instanceof IntPairWritable)) {
return false;
}
IntPairWritable other = (IntPairWritable) obj;
return Arrays.equals(b, other.b);
}
@Override
public int compareTo(BinaryComparable other) {
return Comparator.doCompare(b, 0, ((IntPairWritable) other).b, 0);
}
@Override
public Object clone() {
return new IntPairWritable(this);
}
@Override
public String toString() {
return "(" + getFirst() + ", " + getSecond() + ')';
}
@Override
public byte[] getBytes() {
return b;
}
@Override
public int getLength() {
return INT_PAIR_BYTE_LENGTH;
}
private static void putInt(int value, byte[] b, int offset) {
for (int i = offset, j = 24; j >= 0; i++, j -= 8) {
b[i] = (byte) (value >> j);
}
}
private static int getInt(byte[] b, int offset) {
int value = 0;
for (int i = offset, j = 24; j >= 0; i++, j -= 8) {
value |= (b[i] & 0xFF) << j;
}
return value;
}
static {
WritableComparator.define(IntPairWritable.class, new Comparator());
}
public static final class Comparator extends WritableComparator implements Serializable {
public Comparator() {
super(IntPairWritable.class);
}
@Override
public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
return doCompare(b1, s1, b2, s2);
}
static int doCompare(byte[] b1, int s1, byte[] b2, int s2) {
int compare1 = compareInts(b1, s1, b2, s2);
if (compare1 != 0) {
return compare1;
}
return compareInts(b1, s1 + INT_BYTE_LENGTH, b2, s2 + INT_BYTE_LENGTH);
}
private static int compareInts(byte[] b1, int s1, byte[] b2, int s2) {
// Like WritableComparator.compareBytes(), but treats first byte as signed value
int end1 = s1 + INT_BYTE_LENGTH;
for (int i = s1, j = s2; i < end1; i++, j++) {
int a = b1[i];
int b = b2[j];
if (i > s1) {
a &= 0xff;
b &= 0xff;
}
if (a != b) {
return a - b;
}
}
return 0;
}
}
/**
* Compare only the first part of the pair, so that reduce is called once for each value of the first part.
*/
public static class FirstGroupingComparator extends WritableComparator implements Serializable {
public FirstGroupingComparator() {
super(IntPairWritable.class);
}
@Override
public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
int firstb1 = WritableComparator.readInt(b1, s1);
int firstb2 = WritableComparator.readInt(b2, s2);
if (firstb1 < firstb2) {
return -1;
} else if (firstb1 > firstb2) {
return 1;
} else {
return 0;
}
}
@Override
public int compare(Object o1, Object o2) {
int firstb1 = ((IntPairWritable) o1).getFirst();
int firstb2 = ((IntPairWritable) o2).getFirst();
if (firstb1 < firstb2) {
return -1;
}
if (firstb1 > firstb2) {
return 1;
}
return 0;
}
}
/** A wrapper class that associates pairs with frequency (Occurences) */
public static class Frequency implements Comparable<Frequency>, Serializable {
private final IntPairWritable pair;
private final double frequency;
public Frequency(IntPairWritable bigram, double frequency) {
this.pair = new IntPairWritable(bigram);
this.frequency = frequency;
}
public double getFrequency() {
return frequency;
}
public IntPairWritable getPair() {
return pair;
}
@Override
public int hashCode() {
return pair.hashCode() + RandomUtils.hashDouble(frequency);
}
@Override
public boolean equals(Object right) {
if (!(right instanceof Frequency)) {
return false;
}
Frequency that = (Frequency) right;
return pair.equals(that.pair) && frequency == that.frequency;
}
@Override
public int compareTo(Frequency that) {
if (frequency < that.frequency) {
return -1;
}
if (frequency > that.frequency) {
return 1;
}
return 0;
}
@Override
public String toString() {
return pair + "\t" + frequency;
}
}
}