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A Java's Collaborative Filtering library to carry out experiments in research of Collaborative Filtering based Recommender Systems. The library has been designed from researchers to researchers.
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/*
* 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.commons.math3.linear;
import java.io.Serializable;
import org.apache.commons.math3.Field;
import org.apache.commons.math3.FieldElement;
import org.apache.commons.math3.exception.DimensionMismatchException;
import org.apache.commons.math3.exception.MathArithmeticException;
import org.apache.commons.math3.exception.NotPositiveException;
import org.apache.commons.math3.exception.NullArgumentException;
import org.apache.commons.math3.exception.NumberIsTooSmallException;
import org.apache.commons.math3.exception.OutOfRangeException;
import org.apache.commons.math3.exception.util.LocalizedFormats;
import org.apache.commons.math3.util.MathArrays;
import org.apache.commons.math3.util.MathUtils;
import org.apache.commons.math3.util.OpenIntToFieldHashMap;
/**
* This class implements the {@link FieldVector} interface with a {@link OpenIntToFieldHashMap} backing store.
*
* Caveat: This implementation assumes that, for any {@code x},
* the equality {@code x * 0d == 0d} holds. But it is is not true for
* {@code NaN}. Moreover, zero entries will lose their sign.
* Some operations (that involve {@code NaN} and/or infinities) may
* thus give incorrect results.
*
* @param the type of the field elements
* @since 2.0
*/
public class SparseFieldVector> implements FieldVector, Serializable {
/** Serialization identifier. */
private static final long serialVersionUID = 7841233292190413362L;
/** Field to which the elements belong. */
private final Field field;
/** Entries of the vector. */
private final OpenIntToFieldHashMap entries;
/** Dimension of the vector. */
private final int virtualSize;
/**
* Build a 0-length vector.
* Zero-length vectors may be used to initialize construction of vectors
* by data gathering. We start with zero-length and use either the {@link
* #SparseFieldVector(SparseFieldVector, int)} constructor
* or one of the {@code append} method ({@link #append(FieldVector)} or
* {@link #append(SparseFieldVector)}) to gather data into this vector.
*
* @param field Field to which the elements belong.
*/
public SparseFieldVector(Field field) {
this(field, 0);
}
/**
* Construct a vector of zeroes.
*
* @param field Field to which the elements belong.
* @param dimension Size of the vector.
*/
public SparseFieldVector(Field field, int dimension) {
this.field = field;
virtualSize = dimension;
entries = new OpenIntToFieldHashMap(field);
}
/**
* Build a resized vector, for use with append.
*
* @param v Original vector
* @param resize Amount to add.
*/
protected SparseFieldVector(SparseFieldVector v, int resize) {
field = v.field;
virtualSize = v.getDimension() + resize;
entries = new OpenIntToFieldHashMap(v.entries);
}
/**
* Build a vector with known the sparseness (for advanced use only).
*
* @param field Field to which the elements belong.
* @param dimension Size of the vector.
* @param expectedSize Expected number of non-zero entries.
*/
public SparseFieldVector(Field field, int dimension, int expectedSize) {
this.field = field;
virtualSize = dimension;
entries = new OpenIntToFieldHashMap(field,expectedSize);
}
/**
* Create from a Field array.
* Only non-zero entries will be stored.
*
* @param field Field to which the elements belong.
* @param values Set of values to create from.
* @exception NullArgumentException if values is null
*/
public SparseFieldVector(Field field, T[] values) throws NullArgumentException {
MathUtils.checkNotNull(values);
this.field = field;
virtualSize = values.length;
entries = new OpenIntToFieldHashMap(field);
for (int key = 0; key < values.length; key++) {
T value = values[key];
entries.put(key, value);
}
}
/**
* Copy constructor.
*
* @param v Instance to copy.
*/
public SparseFieldVector(SparseFieldVector v) {
field = v.field;
virtualSize = v.getDimension();
entries = new OpenIntToFieldHashMap(v.getEntries());
}
/**
* Get the entries of this instance.
*
* @return the entries of this instance
*/
private OpenIntToFieldHashMap getEntries() {
return entries;
}
/**
* Optimized method to add sparse vectors.
*
* @param v Vector to add.
* @return {@code this + v}.
* @throws DimensionMismatchException if {@code v} is not the same size as
* {@code this}.
*/
public FieldVector add(SparseFieldVector v)
throws DimensionMismatchException {
checkVectorDimensions(v.getDimension());
SparseFieldVector res = (SparseFieldVector)copy();
OpenIntToFieldHashMap.Iterator iter = v.getEntries().iterator();
while (iter.hasNext()) {
iter.advance();
int key = iter.key();
T value = iter.value();
if (entries.containsKey(key)) {
res.setEntry(key, entries.get(key).add(value));
} else {
res.setEntry(key, value);
}
}
return res;
}
/**
* Construct a vector by appending a vector to this vector.
*
* @param v Vector to append to this one.
* @return a new vector.
*/
public FieldVector append(SparseFieldVector v) {
SparseFieldVector res = new SparseFieldVector(this, v.getDimension());
OpenIntToFieldHashMap.Iterator iter = v.entries.iterator();
while (iter.hasNext()) {
iter.advance();
res.setEntry(iter.key() + virtualSize, iter.value());
}
return res;
}
/** {@inheritDoc} */
public FieldVector append(FieldVector v) {
if (v instanceof SparseFieldVector) {
return append((SparseFieldVector) v);
} else {
final int n = v.getDimension();
FieldVector res = new SparseFieldVector(this, n);
for (int i = 0; i < n; i++) {
res.setEntry(i + virtualSize, v.getEntry(i));
}
return res;
}
}
/** {@inheritDoc}
* @exception NullArgumentException if d is null
*/
public FieldVector append(T d) throws NullArgumentException {
MathUtils.checkNotNull(d);
FieldVector res = new SparseFieldVector(this, 1);
res.setEntry(virtualSize, d);
return res;
}
/** {@inheritDoc} */
public FieldVector copy() {
return new SparseFieldVector(this);
}
/** {@inheritDoc} */
public T dotProduct(FieldVector v) throws DimensionMismatchException {
checkVectorDimensions(v.getDimension());
T res = field.getZero();
OpenIntToFieldHashMap.Iterator iter = entries.iterator();
while (iter.hasNext()) {
iter.advance();
res = res.add(v.getEntry(iter.key()).multiply(iter.value()));
}
return res;
}
/** {@inheritDoc} */
public FieldVector ebeDivide(FieldVector v)
throws DimensionMismatchException, MathArithmeticException {
checkVectorDimensions(v.getDimension());
SparseFieldVector res = new SparseFieldVector(this);
OpenIntToFieldHashMap.Iterator iter = res.entries.iterator();
while (iter.hasNext()) {
iter.advance();
res.setEntry(iter.key(), iter.value().divide(v.getEntry(iter.key())));
}
return res;
}
/** {@inheritDoc} */
public FieldVector ebeMultiply(FieldVector v)
throws DimensionMismatchException {
checkVectorDimensions(v.getDimension());
SparseFieldVector res = new SparseFieldVector(this);
OpenIntToFieldHashMap.Iterator iter = res.entries.iterator();
while (iter.hasNext()) {
iter.advance();
res.setEntry(iter.key(), iter.value().multiply(v.getEntry(iter.key())));
}
return res;
}
/**
* {@inheritDoc}
*
* @deprecated as of 3.1, to be removed in 4.0. Please use the {@link #toArray()} method instead.
*/
@Deprecated
public T[] getData() {
return toArray();
}
/** {@inheritDoc} */
public int getDimension() {
return virtualSize;
}
/** {@inheritDoc} */
public T getEntry(int index) throws OutOfRangeException {
checkIndex(index);
return entries.get(index);
}
/** {@inheritDoc} */
public Field getField() {
return field;
}
/** {@inheritDoc} */
public FieldVector getSubVector(int index, int n)
throws OutOfRangeException, NotPositiveException {
if (n < 0) {
throw new NotPositiveException(LocalizedFormats.NUMBER_OF_ELEMENTS_SHOULD_BE_POSITIVE, n);
}
checkIndex(index);
checkIndex(index + n - 1);
SparseFieldVector res = new SparseFieldVector(field,n);
int end = index + n;
OpenIntToFieldHashMap.Iterator iter = entries.iterator();
while (iter.hasNext()) {
iter.advance();
int key = iter.key();
if (key >= index && key < end) {
res.setEntry(key - index, iter.value());
}
}
return res;
}
/** {@inheritDoc} */
public FieldVector mapAdd(T d) throws NullArgumentException {
return copy().mapAddToSelf(d);
}
/** {@inheritDoc} */
public FieldVector mapAddToSelf(T d) throws NullArgumentException {
for (int i = 0; i < virtualSize; i++) {
setEntry(i, getEntry(i).add(d));
}
return this;
}
/** {@inheritDoc} */
public FieldVector mapDivide(T d)
throws NullArgumentException, MathArithmeticException {
return copy().mapDivideToSelf(d);
}
/** {@inheritDoc} */
public FieldVector mapDivideToSelf(T d)
throws NullArgumentException, MathArithmeticException {
OpenIntToFieldHashMap.Iterator iter = entries.iterator();
while (iter.hasNext()) {
iter.advance();
entries.put(iter.key(), iter.value().divide(d));
}
return this;
}
/** {@inheritDoc} */
public FieldVector mapInv() throws MathArithmeticException {
return copy().mapInvToSelf();
}
/** {@inheritDoc} */
public FieldVector mapInvToSelf() throws MathArithmeticException {
for (int i = 0; i < virtualSize; i++) {
setEntry(i, field.getOne().divide(getEntry(i)));
}
return this;
}
/** {@inheritDoc} */
public FieldVector mapMultiply(T d) throws NullArgumentException {
return copy().mapMultiplyToSelf(d);
}
/** {@inheritDoc} */
public FieldVector mapMultiplyToSelf(T d) throws NullArgumentException {
OpenIntToFieldHashMap.Iterator iter = entries.iterator();
while (iter.hasNext()) {
iter.advance();
entries.put(iter.key(), iter.value().multiply(d));
}
return this;
}
/** {@inheritDoc} */
public FieldVector mapSubtract(T d) throws NullArgumentException {
return copy().mapSubtractToSelf(d);
}
/** {@inheritDoc} */
public FieldVector mapSubtractToSelf(T d) throws NullArgumentException {
return mapAddToSelf(field.getZero().subtract(d));
}
/**
* Optimized method to compute outer product when both vectors are sparse.
* @param v vector with which outer product should be computed
* @return the matrix outer product between instance and v
*/
public FieldMatrix outerProduct(SparseFieldVector v) {
final int n = v.getDimension();
SparseFieldMatrix res = new SparseFieldMatrix(field, virtualSize, n);
OpenIntToFieldHashMap.Iterator iter = entries.iterator();
while (iter.hasNext()) {
iter.advance();
OpenIntToFieldHashMap.Iterator iter2 = v.entries.iterator();
while (iter2.hasNext()) {
iter2.advance();
res.setEntry(iter.key(), iter2.key(), iter.value().multiply(iter2.value()));
}
}
return res;
}
/** {@inheritDoc} */
public FieldMatrix outerProduct(FieldVector v) {
if (v instanceof SparseFieldVector) {
return outerProduct((SparseFieldVector)v);
} else {
final int n = v.getDimension();
FieldMatrix res = new SparseFieldMatrix(field, virtualSize, n);
OpenIntToFieldHashMap.Iterator iter = entries.iterator();
while (iter.hasNext()) {
iter.advance();
int row = iter.key();
FieldElementvalue = iter.value();
for (int col = 0; col < n; col++) {
res.setEntry(row, col, value.multiply(v.getEntry(col)));
}
}
return res;
}
}
/** {@inheritDoc} */
public FieldVector projection(FieldVector v)
throws DimensionMismatchException, MathArithmeticException {
checkVectorDimensions(v.getDimension());
return v.mapMultiply(dotProduct(v).divide(v.dotProduct(v)));
}
/** {@inheritDoc}
* @exception NullArgumentException if value is null
*/
public void set(T value) {
MathUtils.checkNotNull(value);
for (int i = 0; i < virtualSize; i++) {
setEntry(i, value);
}
}
/** {@inheritDoc}
* @exception NullArgumentException if value is null
*/
public void setEntry(int index, T value) throws NullArgumentException, OutOfRangeException {
MathUtils.checkNotNull(value);
checkIndex(index);
entries.put(index, value);
}
/** {@inheritDoc} */
public void setSubVector(int index, FieldVector v)
throws OutOfRangeException {
checkIndex(index);
checkIndex(index + v.getDimension() - 1);
final int n = v.getDimension();
for (int i = 0; i < n; i++) {
setEntry(i + index, v.getEntry(i));
}
}
/**
* Optimized method to compute {@code this} minus {@code v}.
* @param v vector to be subtracted
* @return {@code this - v}
* @throws DimensionMismatchException if {@code v} is not the same size as
* {@code this}.
*/
public SparseFieldVector subtract(SparseFieldVector v)
throws DimensionMismatchException {
checkVectorDimensions(v.getDimension());
SparseFieldVector res = (SparseFieldVector)copy();
OpenIntToFieldHashMap.Iterator iter = v.getEntries().iterator();
while (iter.hasNext()) {
iter.advance();
int key = iter.key();
if (entries.containsKey(key)) {
res.setEntry(key, entries.get(key).subtract(iter.value()));
} else {
res.setEntry(key, field.getZero().subtract(iter.value()));
}
}
return res;
}
/** {@inheritDoc} */
public FieldVector subtract(FieldVector v)
throws DimensionMismatchException {
if (v instanceof SparseFieldVector) {
return subtract((SparseFieldVector)v);
} else {
final int n = v.getDimension();
checkVectorDimensions(n);
SparseFieldVector res = new SparseFieldVector(this);
for (int i = 0; i < n; i++) {
if (entries.containsKey(i)) {
res.setEntry(i, entries.get(i).subtract(v.getEntry(i)));
} else {
res.setEntry(i, field.getZero().subtract(v.getEntry(i)));
}
}
return res;
}
}
/** {@inheritDoc} */
public T[] toArray() {
T[] res = MathArrays.buildArray(field, virtualSize);
OpenIntToFieldHashMap.Iterator iter = entries.iterator();
while (iter.hasNext()) {
iter.advance();
res[iter.key()] = iter.value();
}
return res;
}
/**
* Check whether an index is valid.
*
* @param index Index to check.
* @throws OutOfRangeException if the index is not valid.
*/
private void checkIndex(final int index) throws OutOfRangeException {
if (index < 0 || index >= getDimension()) {
throw new OutOfRangeException(index, 0, getDimension() - 1);
}
}
/**
* Checks that the indices of a subvector are valid.
*
* @param start the index of the first entry of the subvector
* @param end the index of the last entry of the subvector (inclusive)
* @throws OutOfRangeException if {@code start} of {@code end} are not valid
* @throws NumberIsTooSmallException if {@code end < start}
* @since 3.3
*/
private void checkIndices(final int start, final int end)
throws NumberIsTooSmallException, OutOfRangeException {
final int dim = getDimension();
if ((start < 0) || (start >= dim)) {
throw new OutOfRangeException(LocalizedFormats.INDEX, start, 0,
dim - 1);
}
if ((end < 0) || (end >= dim)) {
throw new OutOfRangeException(LocalizedFormats.INDEX, end, 0,
dim - 1);
}
if (end < start) {
throw new NumberIsTooSmallException(LocalizedFormats.INITIAL_ROW_AFTER_FINAL_ROW,
end, start, false);
}
}
/**
* Check if instance dimension is equal to some expected value.
*
* @param n Expected dimension.
* @throws DimensionMismatchException if the dimensions do not match.
*/
protected void checkVectorDimensions(int n)
throws DimensionMismatchException {
if (getDimension() != n) {
throw new DimensionMismatchException(getDimension(), n);
}
}
/** {@inheritDoc} */
public FieldVector add(FieldVector v) throws DimensionMismatchException {
if (v instanceof SparseFieldVector) {
return add((SparseFieldVector) v);
} else {
final int n = v.getDimension();
checkVectorDimensions(n);
SparseFieldVector res = new SparseFieldVector(field,
getDimension());
for (int i = 0; i < n; i++) {
res.setEntry(i, v.getEntry(i).add(getEntry(i)));
}
return res;
}
}
/**
* Visits (but does not alter) all entries of this vector in default order
* (increasing index).
*
* @param visitor the visitor to be used to process the entries of this
* vector
* @return the value returned by {@link FieldVectorPreservingVisitor#end()}
* at the end of the walk
* @since 3.3
*/
public T walkInDefaultOrder(final FieldVectorPreservingVisitor visitor) {
final int dim = getDimension();
visitor.start(dim, 0, dim - 1);
for (int i = 0; i < dim; i++) {
visitor.visit(i, getEntry(i));
}
return visitor.end();
}
/**
* Visits (but does not alter) some entries of this vector in default order
* (increasing index).
*
* @param visitor visitor to be used to process the entries of this vector
* @param start the index of the first entry to be visited
* @param end the index of the last entry to be visited (inclusive)
* @return the value returned by {@link FieldVectorPreservingVisitor#end()}
* at the end of the walk
* @throws NumberIsTooSmallException if {@code end < start}.
* @throws OutOfRangeException if the indices are not valid.
* @since 3.3
*/
public T walkInDefaultOrder(final FieldVectorPreservingVisitor visitor,
final int start, final int end)
throws NumberIsTooSmallException, OutOfRangeException {
checkIndices(start, end);
visitor.start(getDimension(), start, end);
for (int i = start; i <= end; i++) {
visitor.visit(i, getEntry(i));
}
return visitor.end();
}
/**
* Visits (but does not alter) all entries of this vector in optimized
* order. The order in which the entries are visited is selected so as to
* lead to the most efficient implementation; it might depend on the
* concrete implementation of this abstract class.
*
* @param visitor the visitor to be used to process the entries of this
* vector
* @return the value returned by {@link FieldVectorPreservingVisitor#end()}
* at the end of the walk
* @since 3.3
*/
public T walkInOptimizedOrder(final FieldVectorPreservingVisitor visitor) {
return walkInDefaultOrder(visitor);
}
/**
* Visits (but does not alter) some entries of this vector in optimized
* order. The order in which the entries are visited is selected so as to
* lead to the most efficient implementation; it might depend on the
* concrete implementation of this abstract class.
*
* @param visitor visitor to be used to process the entries of this vector
* @param start the index of the first entry to be visited
* @param end the index of the last entry to be visited (inclusive)
* @return the value returned by {@link FieldVectorPreservingVisitor#end()}
* at the end of the walk
* @throws NumberIsTooSmallException if {@code end < start}.
* @throws OutOfRangeException if the indices are not valid.
* @since 3.3
*/
public T walkInOptimizedOrder(final FieldVectorPreservingVisitor visitor,
final int start, final int end)
throws NumberIsTooSmallException, OutOfRangeException {
return walkInDefaultOrder(visitor, start, end);
}
/**
* Visits (and possibly alters) all entries of this vector in default order
* (increasing index).
*
* @param visitor the visitor to be used to process and modify the entries
* of this vector
* @return the value returned by {@link FieldVectorChangingVisitor#end()}
* at the end of the walk
* @since 3.3
*/
public T walkInDefaultOrder(final FieldVectorChangingVisitor visitor) {
final int dim = getDimension();
visitor.start(dim, 0, dim - 1);
for (int i = 0; i < dim; i++) {
setEntry(i, visitor.visit(i, getEntry(i)));
}
return visitor.end();
}
/**
* Visits (and possibly alters) some entries of this vector in default order
* (increasing index).
*
* @param visitor visitor to be used to process the entries of this vector
* @param start the index of the first entry to be visited
* @param end the index of the last entry to be visited (inclusive)
* @return the value returned by {@link FieldVectorChangingVisitor#end()}
* at the end of the walk
* @throws NumberIsTooSmallException if {@code end < start}.
* @throws OutOfRangeException if the indices are not valid.
* @since 3.3
*/
public T walkInDefaultOrder(final FieldVectorChangingVisitor visitor,
final int start, final int end)
throws NumberIsTooSmallException, OutOfRangeException {
checkIndices(start, end);
visitor.start(getDimension(), start, end);
for (int i = start; i <= end; i++) {
setEntry(i, visitor.visit(i, getEntry(i)));
}
return visitor.end();
}
/**
* Visits (and possibly alters) all entries of this vector in optimized
* order. The order in which the entries are visited is selected so as to
* lead to the most efficient implementation; it might depend on the
* concrete implementation of this abstract class.
*
* @param visitor the visitor to be used to process the entries of this
* vector
* @return the value returned by {@link FieldVectorChangingVisitor#end()}
* at the end of the walk
* @since 3.3
*/
public T walkInOptimizedOrder(final FieldVectorChangingVisitor visitor) {
return walkInDefaultOrder(visitor);
}
/**
* Visits (and possibly change) some entries of this vector in optimized
* order. The order in which the entries are visited is selected so as to
* lead to the most efficient implementation; it might depend on the
* concrete implementation of this abstract class.
*
* @param visitor visitor to be used to process the entries of this vector
* @param start the index of the first entry to be visited
* @param end the index of the last entry to be visited (inclusive)
* @return the value returned by {@link FieldVectorChangingVisitor#end()}
* at the end of the walk
* @throws NumberIsTooSmallException if {@code end < start}.
* @throws OutOfRangeException if the indices are not valid.
* @since 3.3
*/
public T walkInOptimizedOrder(final FieldVectorChangingVisitor visitor,
final int start, final int end)
throws NumberIsTooSmallException, OutOfRangeException {
return walkInDefaultOrder(visitor, start, end);
}
/** {@inheritDoc} */
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((field == null) ? 0 : field.hashCode());
result = prime * result + virtualSize;
OpenIntToFieldHashMap.Iterator iter = entries.iterator();
while (iter.hasNext()) {
iter.advance();
int temp = iter.value().hashCode();
result = prime * result + temp;
}
return result;
}
/** {@inheritDoc} */
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (!(obj instanceof SparseFieldVector)) {
return false;
}
@SuppressWarnings("unchecked") // OK, because "else if" check below ensures that
// other must be the same type as this
SparseFieldVector other = (SparseFieldVector) obj;
if (field == null) {
if (other.field != null) {
return false;
}
} else if (!field.equals(other.field)) {
return false;
}
if (virtualSize != other.virtualSize) {
return false;
}
OpenIntToFieldHashMap.Iterator iter = entries.iterator();
while (iter.hasNext()) {
iter.advance();
T test = other.getEntry(iter.key());
if (!test.equals(iter.value())) {
return false;
}
}
iter = other.getEntries().iterator();
while (iter.hasNext()) {
iter.advance();
T test = iter.value();
if (!test.equals(getEntry(iter.key()))) {
return false;
}
}
return true;
}
}
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