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Part of MAHOUT-1202.
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Extended OrderedIntDoubleMapping to support merging and zero values.
This is required for faster SequentialAccessSparseVector updates.



git-svn-id: https://svn.apache.org/repos/asf/mahout/trunk@1478865 13f79535-47bb-0310-9956-ffa450edef68
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Dan Filimon committed May 3, 2013
1 parent 5f859ab commit bf82164
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Showing 2 changed files with 115 additions and 15 deletions.
97 changes: 82 additions & 15 deletions math/src/main/java/org/apache/mahout/math/OrderedIntDoubleMapping.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -19,14 +19,23 @@

import java.io.Serializable;

final class OrderedIntDoubleMapping implements Serializable, Cloneable {
public final class OrderedIntDoubleMapping implements Serializable, Cloneable {

static final double DEFAULT_VALUE = 0.0;

private int[] indices;
private double[] values;
private int numMappings;

// If true, doesn't allow DEFAULT_VALUEs in the mapping (adding a zero discards it). Otherwise, a DEFAULT_VALUE is
// treated like any other value.
private boolean noDefault = true;

OrderedIntDoubleMapping(boolean noDefault) {
this();
this.noDefault = noDefault;
}

OrderedIntDoubleMapping() {
// no-arg constructor for deserializer
this(11);
Expand All @@ -44,28 +53,28 @@ final class OrderedIntDoubleMapping implements Serializable, Cloneable {
this.numMappings = numMappings;
}

int[] getIndices() {
public int[] getIndices() {
return indices;
}

int indexAt(int offset) {
public int indexAt(int offset) {
return indices[offset];
}

void setIndexAt(int offset, int index) {
public void setIndexAt(int offset, int index) {
indices[offset] = index;
}

double[] getValues() {
public double[] getValues() {
return values;
}

void setValueAt(int offset, double value) {
public void setValueAt(int offset, double value) {
values[offset] = value;
}


int getNumMappings() {
public int getNumMappings() {
return numMappings;
}

Expand Down Expand Up @@ -103,12 +112,70 @@ public double get(int index) {
}

public void set(int index, double value) {
int offset = find(index);
if (offset >= 0) {
insertOrUpdateValueIfPresent(offset, value);
if (numMappings == 0 || index > indices[numMappings - 1]) {
if (!noDefault || value != DEFAULT_VALUE) {
if (numMappings >= indices.length) {
growTo(Math.max((int) (1.2 * numMappings), numMappings + 1));
}
indices[numMappings] = index;
values[numMappings] = value;
++numMappings;
}
} else {
insertValueIfNotDefault(index, offset, value);
int offset = find(index);
if (offset >= 0) {
insertOrUpdateValueIfPresent(offset, value);
} else {
insertValueIfNotDefault(index, offset, value);
}
}
}

/**
* Merges the updates in linear time by allocating new arrays and iterating through the existing indices and values
* and the updates' indices and values at the same time while selecting the minimum index to set at each step.
* @param updates another list of mappings to be merged in.
*/
public void merge(OrderedIntDoubleMapping updates) {
int updateIndices[] = updates.getIndices();
double updateValues[] = updates.getValues();

int newNumMappings = numMappings + updates.getNumMappings();
int newCapacity = Math.max((int) (1.2 * newNumMappings), newNumMappings + 1);
int newIndices[] = new int[newCapacity];
double newValues[] = new double[newCapacity];

int k = 0;
int i = 0, j = 0;
for (; i < numMappings && j < updates.getNumMappings(); ++k) {
if (indices[i] < updateIndices[j]) {
newIndices[k] = indices[i];
newValues[k] = values[i];
++i;
} else if (indices[i] > updateIndices[j]) {
newIndices[k] = updateIndices[j];
newValues[k] = updateValues[j];
++j;
} else {
newIndices[k] = updateIndices[j];
newValues[k] = updateValues[j];
++i;
++j;
}
}

for (; i < numMappings; ++i, ++k) {
newIndices[k] = indices[i];
newValues[k] = values[i];
}
for (; j < updates.getNumMappings(); ++j, ++k) {
newIndices[k] = updateIndices[j];
newValues[k] = updateValues[j];
}

indices = newIndices;
values = newValues;
numMappings = k;
}

@Override
Expand Down Expand Up @@ -150,6 +217,7 @@ public String toString() {
return result.toString();
}

@SuppressWarnings("CloneDoesntCallSuperClone")
@Override
public OrderedIntDoubleMapping clone() {
return new OrderedIntDoubleMapping(indices.clone(), values.clone(), numMappings);
Expand All @@ -161,13 +229,12 @@ public void increment(int index, double increment) {
double newValue = values[offset] + increment;
insertOrUpdateValueIfPresent(offset, newValue);
} else {
double newValue = increment;
insertValueIfNotDefault(index, offset, newValue);
insertValueIfNotDefault(index, offset, increment);
}
}

private void insertValueIfNotDefault(int index, int offset, double value) {
if (value != DEFAULT_VALUE) {
if (!noDefault || value != DEFAULT_VALUE) {
if (numMappings >= indices.length) {
growTo(Math.max((int) (1.2 * numMappings), numMappings + 1));
}
Expand All @@ -185,7 +252,7 @@ private void insertValueIfNotDefault(int index, int offset, double value) {
}

private void insertOrUpdateValueIfPresent(int offset, double newValue) {
if (newValue == DEFAULT_VALUE) {
if (noDefault && newValue == DEFAULT_VALUE) {
for (int i = offset + 1, j = offset; i < numMappings; i++, j++) {
indices[j] = indices[i];
values[j] = values[i];
Expand Down
33 changes: 33 additions & 0 deletions math/src/test/java/org/apache/mahout/math/TestOrderedIntDoubleMapping.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -68,4 +68,37 @@ public void testClone() throws Exception {
assertEquals(0.0, clone.get(6), EPSILON);
}

@Test
public void testAddDefaultElements() {
OrderedIntDoubleMapping mapping = new OrderedIntDoubleMapping(false);
mapping.set(1, 1.1);
assertEquals(1, mapping.getNumMappings());
mapping.set(2, 0);
assertEquals(2, mapping.getNumMappings());
mapping.set(0, 0);
assertEquals(3, mapping.getNumMappings());
}

@Test
public void testMerge() {
OrderedIntDoubleMapping mappingOne = new OrderedIntDoubleMapping(false);
mappingOne.set(0, 0);
mappingOne.set(2, 2);
mappingOne.set(4, 4);
mappingOne.set(10, 10);

OrderedIntDoubleMapping mappingTwo = new OrderedIntDoubleMapping();
mappingTwo.set(1, 1);
mappingTwo.set(3, 3);
mappingTwo.set(5, 5);
mappingTwo.set(10, 20);

mappingOne.merge(mappingTwo);

assertEquals(7, mappingOne.getNumMappings());
for (int i = 0; i < 6; ++i) {
assertEquals(i, mappingOne.get(i), i);
}
assertEquals(20, mappingOne.get(10), 0);
}
}

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