/**
* 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.math;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.io.Writable;
import com.google.common.base.Preconditions;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Iterator;
public final class VectorWritable extends Configured implements Writable {
public static final int FLAG_DENSE = 0x01;
public static final int FLAG_SEQUENTIAL = 0x02;
public static final int FLAG_NAMED = 0x04;
public static final int FLAG_LAX_PRECISION = 0x08;
public static final int NUM_FLAGS = 4;
private Vector vector;
private boolean writesLaxPrecision;
public VectorWritable() {
}
public VectorWritable(Vector vector) {
this.vector = vector;
}
public VectorWritable(Vector vector, boolean writesLaxPrecision) {
this(vector);
setWritesLaxPrecision(writesLaxPrecision);
}
/**
* @return {@link Vector} that this is to write, or has
* just read
*/
public Vector get() {
return vector;
}
public void set(Vector vector) {
this.vector = vector;
}
/**
* @return true if this is allowed to encode {@link Vector}
* values using fewer bytes, possibly losing precision. In particular this means
* that floating point values will be encoded as floats, not doubles.
*/
public boolean isWritesLaxPrecision() {
return writesLaxPrecision;
}
public void setWritesLaxPrecision(boolean writesLaxPrecision) {
this.writesLaxPrecision = writesLaxPrecision;
}
@Override
public void write(DataOutput out) throws IOException {
writeVector(out, this.vector, this.writesLaxPrecision);
}
@Override
public void readFields(DataInput in) throws IOException {
int flags = in.readByte();
Preconditions.checkArgument(flags >> NUM_FLAGS == 0, "Unknown flags set: %d", Integer.toString(flags, 2));
boolean dense = (flags & FLAG_DENSE) != 0;
boolean sequential = (flags & FLAG_SEQUENTIAL) != 0;
boolean named = (flags & FLAG_NAMED) != 0;
boolean laxPrecision = (flags & FLAG_LAX_PRECISION) != 0;
int size = Varint.readUnsignedVarInt(in);
Vector v;
if (dense) {
double[] values = new double[size];
for (int i = 0; i < size; i++) {
values[i] = laxPrecision ? in.readFloat() : in.readDouble();
}
v = new DenseVector(values);
} else {
int numNonDefaultElements = Varint.readUnsignedVarInt(in);
v = sequential
? new SequentialAccessSparseVector(size, numNonDefaultElements)
: new RandomAccessSparseVector(size, numNonDefaultElements);
if (sequential) {
int lastIndex = 0;
for (int i = 0; i < numNonDefaultElements; i++) {
int delta = Varint.readUnsignedVarInt(in);
int index = lastIndex + delta;
lastIndex = index;
double value = laxPrecision ? in.readFloat() : in.readDouble();
v.setQuick(index, value);
}
} else {
for (int i = 0; i < numNonDefaultElements; i++) {
int index = Varint.readUnsignedVarInt(in);
double value = laxPrecision ? in.readFloat() : in.readDouble();
v.setQuick(index, value);
}
}
}
if (named) {
String name = in.readUTF();
v = new NamedVector(v, name);
}
vector = v;
}
/** Write the vector to the output */
public static void writeVector(DataOutput out, Vector vector) throws IOException {
writeVector(out, vector, false);
}
public static void writeVector(DataOutput out, Vector vector, boolean laxPrecision) throws IOException {
boolean dense = vector.isDense();
boolean sequential = vector.isSequentialAccess();
boolean named = vector instanceof NamedVector;
out.writeByte((dense ? FLAG_DENSE : 0)
| (sequential ? FLAG_SEQUENTIAL : 0)
| (named ? FLAG_NAMED : 0)
| (laxPrecision ? FLAG_LAX_PRECISION : 0));
Varint.writeUnsignedVarInt(vector.size(), out);
if (dense) {
for (Vector.Element element : vector) {
if (laxPrecision) {
out.writeFloat((float) element.get());
} else {
out.writeDouble(element.get());
}
}
} else {
Varint.writeUnsignedVarInt(vector.getNumNondefaultElements(), out);
Iterator<Vector.Element> iter = vector.iterateNonZero();
if (sequential) {
int lastIndex = 0;
while (iter.hasNext()) {
Vector.Element element = iter.next();
int thisIndex = element.index();
// Delta-code indices:
Varint.writeUnsignedVarInt(thisIndex - lastIndex, out);
lastIndex = thisIndex;
if (laxPrecision) {
out.writeFloat((float) element.get());
} else {
out.writeDouble(element.get());
}
}
} else {
while (iter.hasNext()) {
Vector.Element element = iter.next();
Varint.writeUnsignedVarInt(element.index(), out);
if (laxPrecision) {
out.writeFloat((float) element.get());
} else {
out.writeDouble(element.get());
}
}
}
}
if (named) {
String name = ((NamedVector) vector).getName();
out.writeUTF(name == null ? "" : name);
}
}
public static Vector readVector(DataInput in) throws IOException {
VectorWritable v = new VectorWritable();
v.readFields(in);
return v.get();
}
public static VectorWritable merge(Iterator<VectorWritable> vectors) {
Vector accumulator = vectors.next().get();
while (vectors.hasNext()) {
VectorWritable v = vectors.next();
if (v != null) {
Iterator<Vector.Element> nonZeroElements = v.get().iterateNonZero();
while (nonZeroElements.hasNext()) {
Vector.Element nonZeroElement = nonZeroElements.next();
accumulator.setQuick(nonZeroElement.index(), nonZeroElement.get());
}
}
}
return new VectorWritable(accumulator);
}
@Override
public boolean equals(Object o) {
return o instanceof VectorWritable && vector.equals(((VectorWritable) o).get());
}
@Override
public int hashCode() {
return vector.hashCode();
}
@Override
public String toString() {
return vector.toString();
}
}