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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.util.Iterator;
import java.util.NoSuchElementException;
import org.apache.commons.math3.exception.MathUnsupportedOperationException;
import org.apache.commons.math3.exception.DimensionMismatchException;
import org.apache.commons.math3.exception.NotPositiveException;
import org.apache.commons.math3.exception.NumberIsTooSmallException;
import org.apache.commons.math3.exception.OutOfRangeException;
import org.apache.commons.math3.exception.MathArithmeticException;
import org.apache.commons.math3.analysis.FunctionUtils;
import org.apache.commons.math3.analysis.function.Add;
import org.apache.commons.math3.analysis.function.Multiply;
import org.apache.commons.math3.analysis.function.Divide;
import org.apache.commons.math3.analysis.UnivariateFunction;
import org.apache.commons.math3.exception.util.LocalizedFormats;
import org.apache.commons.math3.util.FastMath;
/**
* Class defining a real-valued vector with basic algebraic operations.
*
* vector element indexing is 0-based -- e.g., {@code getEntry(0)}
* returns the first element of the vector.
*
*
* The {@code code map} and {@code mapToSelf} methods operate
* on vectors element-wise, i.e. they perform the same operation (adding a scalar,
* applying a function ...) on each element in turn. The {@code map}
* versions create a new vector to hold the result and do not change the instance.
* The {@code mapToSelf} version uses the instance itself to store the
* results, so the instance is changed by this method. In all cases, the result
* vector is returned by the methods, allowing the fluent API
* style, like this:
*
*
* RealVector result = v.mapAddToSelf(3.4).mapToSelf(new Tan()).mapToSelf(new Power(2.3));
*
*
* @since 2.1
*/
public abstract class RealVector {
/**
* Returns the size of the vector.
*
* @return the size of this vector.
*/
public abstract int getDimension();
/**
* Return the entry at the specified index.
*
* @param index Index location of entry to be fetched.
* @return the vector entry at {@code index}.
* @throws OutOfRangeException if the index is not valid.
* @see #setEntry(int, double)
*/
public abstract double getEntry(int index) throws OutOfRangeException;
/**
* Set a single element.
*
* @param index element index.
* @param value new value for the element.
* @throws OutOfRangeException if the index is not valid.
* @see #getEntry(int)
*/
public abstract void setEntry(int index, double value)
throws OutOfRangeException;
/**
* Change an entry at the specified index.
*
* @param index Index location of entry to be set.
* @param increment Value to add to the vector entry.
* @throws OutOfRangeException if the index is not valid.
* @since 3.0
*/
public void addToEntry(int index, double increment)
throws OutOfRangeException {
setEntry(index, getEntry(index) + increment);
}
/**
* Construct a new vector by appending a vector to this vector.
*
* @param v vector to append to this one.
* @return a new vector.
*/
public abstract RealVector append(RealVector v);
/**
* Construct a new vector by appending a double to this vector.
*
* @param d double to append.
* @return a new vector.
*/
public abstract RealVector append(double d);
/**
* Get a subvector from consecutive elements.
*
* @param index index of first element.
* @param n number of elements to be retrieved.
* @return a vector containing n elements.
* @throws OutOfRangeException if the index is not valid.
* @throws NotPositiveException if the number of elements is not positive.
*/
public abstract RealVector getSubVector(int index, int n)
throws NotPositiveException, OutOfRangeException;
/**
* Set a sequence of consecutive elements.
*
* @param index index of first element to be set.
* @param v vector containing the values to set.
* @throws OutOfRangeException if the index is not valid.
*/
public abstract void setSubVector(int index, RealVector v)
throws OutOfRangeException;
/**
* Check whether any coordinate of this vector is {@code NaN}.
*
* @return {@code true} if any coordinate of this vector is {@code NaN},
* {@code false} otherwise.
*/
public abstract boolean isNaN();
/**
* Check whether any coordinate of this vector is infinite and none are {@code NaN}.
*
* @return {@code true} if any coordinate of this vector is infinite and
* none are {@code NaN}, {@code false} otherwise.
*/
public abstract boolean isInfinite();
/**
* Check if instance and specified vectors have the same dimension.
*
* @param v Vector to compare instance with.
* @throws DimensionMismatchException if the vectors do not
* have the same dimension.
*/
protected void checkVectorDimensions(RealVector v)
throws DimensionMismatchException {
checkVectorDimensions(v.getDimension());
}
/**
* Check if instance dimension is equal to some expected value.
*
* @param n Expected dimension.
* @throws DimensionMismatchException if the dimension is
* inconsistent with the vector size.
*/
protected void checkVectorDimensions(int n)
throws DimensionMismatchException {
int d = getDimension();
if (d != n) {
throw new DimensionMismatchException(d, n);
}
}
/**
* Check if an index is valid.
*
* @param index Index to check.
* @exception OutOfRangeException if {@code index} is not valid.
*/
protected void checkIndex(final int index) throws OutOfRangeException {
if (index < 0 ||
index >= getDimension()) {
throw new OutOfRangeException(LocalizedFormats.INDEX,
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 3.1
*/
protected 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) {
// TODO Use more specific error message
throw new NumberIsTooSmallException(LocalizedFormats.INITIAL_ROW_AFTER_FINAL_ROW,
end, start, false);
}
}
/**
* Compute the sum of this vector and {@code v}.
* Returns a new vector. Does not change instance data.
*
* @param v Vector to be added.
* @return {@code this} + {@code v}.
* @throws DimensionMismatchException if {@code v} is not the same size as
* {@code this} vector.
*/
public RealVector add(RealVector v) throws DimensionMismatchException {
checkVectorDimensions(v);
RealVector result = v.copy();
Iterator it = iterator();
while (it.hasNext()) {
final Entry e = it.next();
final int index = e.getIndex();
result.setEntry(index, e.getValue() + result.getEntry(index));
}
return result;
}
/**
* Subtract {@code v} from this vector.
* Returns a new vector. Does not change instance data.
*
* @param v Vector to be subtracted.
* @return {@code this} - {@code v}.
* @throws DimensionMismatchException if {@code v} is not the same size as
* {@code this} vector.
*/
public RealVector subtract(RealVector v) throws DimensionMismatchException {
checkVectorDimensions(v);
RealVector result = v.mapMultiply(-1d);
Iterator it = iterator();
while (it.hasNext()) {
final Entry e = it.next();
final int index = e.getIndex();
result.setEntry(index, e.getValue() + result.getEntry(index));
}
return result;
}
/**
* Add a value to each entry.
* Returns a new vector. Does not change instance data.
*
* @param d Value to be added to each entry.
* @return {@code this} + {@code d}.
*/
public RealVector mapAdd(double d) {
return copy().mapAddToSelf(d);
}
/**
* Add a value to each entry.
* The instance is changed in-place.
*
* @param d Value to be added to each entry.
* @return {@code this}.
*/
public RealVector mapAddToSelf(double d) {
if (d != 0) {
return mapToSelf(FunctionUtils.fix2ndArgument(new Add(), d));
}
return this;
}
/**
* Returns a (deep) copy of this vector.
*
* @return a vector copy.
*/
public abstract RealVector copy();
/**
* Compute the dot product of this vector with {@code v}.
*
* @param v Vector with which dot product should be computed
* @return the scalar dot product between this instance and {@code v}.
* @throws DimensionMismatchException if {@code v} is not the same size as
* {@code this} vector.
*/
public double dotProduct(RealVector v) throws DimensionMismatchException {
checkVectorDimensions(v);
double d = 0;
final int n = getDimension();
for (int i = 0; i < n; i++) {
d += getEntry(i) * v.getEntry(i);
}
return d;
}
/**
* Computes the cosine of the angle between this vector and the
* argument.
*
* @param v Vector.
* @return the cosine of the angle between this vector and {@code v}.
* @throws MathArithmeticException if {@code this} or {@code v} is the null
* vector
* @throws DimensionMismatchException if the dimensions of {@code this} and
* {@code v} do not match
*/
public double cosine(RealVector v) throws DimensionMismatchException,
MathArithmeticException {
final double norm = getNorm();
final double vNorm = v.getNorm();
if (norm == 0 ||
vNorm == 0) {
throw new MathArithmeticException(LocalizedFormats.ZERO_NORM);
}
return dotProduct(v) / (norm * vNorm);
}
/**
* Element-by-element division.
*
* @param v Vector by which instance elements must be divided.
* @return a vector containing this[i] / v[i] for all i.
* @throws DimensionMismatchException if {@code v} is not the same size as
* {@code this} vector.
*/
public abstract RealVector ebeDivide(RealVector v)
throws DimensionMismatchException;
/**
* Element-by-element multiplication.
*
* @param v Vector by which instance elements must be multiplied
* @return a vector containing this[i] * v[i] for all i.
* @throws DimensionMismatchException if {@code v} is not the same size as
* {@code this} vector.
*/
public abstract RealVector ebeMultiply(RealVector v)
throws DimensionMismatchException;
/**
* Distance between two vectors.
* This method computes the distance consistent with the
* L2 norm, i.e. the square root of the sum of
* element differences, or Euclidean distance.
*
* @param v Vector to which distance is requested.
* @return the distance between two vectors.
* @throws DimensionMismatchException if {@code v} is not the same size as
* {@code this} vector.
* @see #getL1Distance(RealVector)
* @see #getLInfDistance(RealVector)
* @see #getNorm()
*/
public double getDistance(RealVector v) throws DimensionMismatchException {
checkVectorDimensions(v);
double d = 0;
Iterator it = iterator();
while (it.hasNext()) {
final Entry e = it.next();
final double diff = e.getValue() - v.getEntry(e.getIndex());
d += diff * diff;
}
return FastMath.sqrt(d);
}
/**
* Returns the L2 norm of the vector.
* The L2 norm is the root of the sum of
* the squared elements.
*
* @return the norm.
* @see #getL1Norm()
* @see #getLInfNorm()
* @see #getDistance(RealVector)
*/
public double getNorm() {
double sum = 0;
Iterator it = iterator();
while (it.hasNext()) {
final Entry e = it.next();
final double value = e.getValue();
sum += value * value;
}
return FastMath.sqrt(sum);
}
/**
* Returns the L1 norm of the vector.
* The L1 norm is the sum of the absolute
* values of the elements.
*
* @return the norm.
* @see #getNorm()
* @see #getLInfNorm()
* @see #getL1Distance(RealVector)
*/
public double getL1Norm() {
double norm = 0;
Iterator it = iterator();
while (it.hasNext()) {
final Entry e = it.next();
norm += FastMath.abs(e.getValue());
}
return norm;
}
/**
* Returns the L∞ norm of the vector.
* The L∞ norm is the max of the absolute
* values of the elements.
*
* @return the norm.
* @see #getNorm()
* @see #getL1Norm()
* @see #getLInfDistance(RealVector)
*/
public double getLInfNorm() {
double norm = 0;
Iterator it = iterator();
while (it.hasNext()) {
final Entry e = it.next();
norm = FastMath.max(norm, FastMath.abs(e.getValue()));
}
return norm;
}
/**
* Distance between two vectors.
* This method computes the distance consistent with
* L1 norm, i.e. the sum of the absolute values of
* the elements differences.
*
* @param v Vector to which distance is requested.
* @return the distance between two vectors.
* @throws DimensionMismatchException if {@code v} is not the same size as
* {@code this} vector.
*/
public double getL1Distance(RealVector v)
throws DimensionMismatchException {
checkVectorDimensions(v);
double d = 0;
Iterator it = iterator();
while (it.hasNext()) {
final Entry e = it.next();
d += FastMath.abs(e.getValue() - v.getEntry(e.getIndex()));
}
return d;
}
/**
* Distance between two vectors.
* This method computes the distance consistent with
* L∞ norm, i.e. the max of the absolute values of
* element differences.
*
* @param v Vector to which distance is requested.
* @return the distance between two vectors.
* @throws DimensionMismatchException if {@code v} is not the same size as
* {@code this} vector.
* @see #getDistance(RealVector)
* @see #getL1Distance(RealVector)
* @see #getLInfNorm()
*/
public double getLInfDistance(RealVector v)
throws DimensionMismatchException {
checkVectorDimensions(v);
double d = 0;
Iterator it = iterator();
while (it.hasNext()) {
final Entry e = it.next();
d = FastMath.max(FastMath.abs(e.getValue() - v.getEntry(e.getIndex())), d);
}
return d;
}
/**
* Get the index of the minimum entry.
*
* @return the index of the minimum entry or -1 if vector length is 0
* or all entries are {@code NaN}.
*/
public int getMinIndex() {
int minIndex = -1;
double minValue = Double.POSITIVE_INFINITY;
Iterator iterator = iterator();
while (iterator.hasNext()) {
final Entry entry = iterator.next();
if (entry.getValue() <= minValue) {
minIndex = entry.getIndex();
minValue = entry.getValue();
}
}
return minIndex;
}
/**
* Get the value of the minimum entry.
*
* @return the value of the minimum entry or {@code NaN} if all
* entries are {@code NaN}.
*/
public double getMinValue() {
final int minIndex = getMinIndex();
return minIndex < 0 ? Double.NaN : getEntry(minIndex);
}
/**
* Get the index of the maximum entry.
*
* @return the index of the maximum entry or -1 if vector length is 0
* or all entries are {@code NaN}
*/
public int getMaxIndex() {
int maxIndex = -1;
double maxValue = Double.NEGATIVE_INFINITY;
Iterator iterator = iterator();
while (iterator.hasNext()) {
final Entry entry = iterator.next();
if (entry.getValue() >= maxValue) {
maxIndex = entry.getIndex();
maxValue = entry.getValue();
}
}
return maxIndex;
}
/**
* Get the value of the maximum entry.
*
* @return the value of the maximum entry or {@code NaN} if all
* entries are {@code NaN}.
*/
public double getMaxValue() {
final int maxIndex = getMaxIndex();
return maxIndex < 0 ? Double.NaN : getEntry(maxIndex);
}
/**
* Multiply each entry by the argument. Returns a new vector.
* Does not change instance data.
*
* @param d Multiplication factor.
* @return {@code this} * {@code d}.
*/
public RealVector mapMultiply(double d) {
return copy().mapMultiplyToSelf(d);
}
/**
* Multiply each entry.
* The instance is changed in-place.
*
* @param d Multiplication factor.
* @return {@code this}.
*/
public RealVector mapMultiplyToSelf(double d){
return mapToSelf(FunctionUtils.fix2ndArgument(new Multiply(), d));
}
/**
* Subtract a value from each entry. Returns a new vector.
* Does not change instance data.
*
* @param d Value to be subtracted.
* @return {@code this} - {@code d}.
*/
public RealVector mapSubtract(double d) {
return copy().mapSubtractToSelf(d);
}
/**
* Subtract a value from each entry.
* The instance is changed in-place.
*
* @param d Value to be subtracted.
* @return {@code this}.
*/
public RealVector mapSubtractToSelf(double d){
return mapAddToSelf(-d);
}
/**
* Divide each entry by the argument. Returns a new vector.
* Does not change instance data.
*
* @param d Value to divide by.
* @return {@code this} / {@code d}.
*/
public RealVector mapDivide(double d) {
return copy().mapDivideToSelf(d);
}
/**
* Divide each entry by the argument.
* The instance is changed in-place.
*
* @param d Value to divide by.
* @return {@code this}.
*/
public RealVector mapDivideToSelf(double d){
return mapToSelf(FunctionUtils.fix2ndArgument(new Divide(), d));
}
/**
* Compute the outer product.
*
* @param v Vector with which outer product should be computed.
* @return the matrix outer product between this instance and {@code v}.
*/
public RealMatrix outerProduct(RealVector v) {
final int m = this.getDimension();
final int n = v.getDimension();
final RealMatrix product;
if (v instanceof SparseRealVector || this instanceof SparseRealVector) {
product = new OpenMapRealMatrix(m, n);
} else {
product = new Array2DRowRealMatrix(m, n);
}
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
product.setEntry(i, j, this.getEntry(i) * v.getEntry(j));
}
}
return product;
}
/**
* Find the orthogonal projection of this vector onto another vector.
*
* @param v vector onto which instance must be projected.
* @return projection of the instance onto {@code v}.
* @throws DimensionMismatchException if {@code v} is not the same size as
* {@code this} vector.
* @throws MathArithmeticException if {@code this} or {@code v} is the null
* vector
*/
public RealVector projection(final RealVector v)
throws DimensionMismatchException, MathArithmeticException {
final double norm2 = v.dotProduct(v);
if (norm2 == 0.0) {
throw new MathArithmeticException(LocalizedFormats.ZERO_NORM);
}
return v.mapMultiply(dotProduct(v) / v.dotProduct(v));
}
/**
* Set all elements to a single value.
*
* @param value Single value to set for all elements.
*/
public void set(double value) {
Iterator it = iterator();
while (it.hasNext()) {
final Entry e = it.next();
e.setValue(value);
}
}
/**
* Convert the vector to an array of {@code double}s.
* The array is independent from this vector data: the elements
* are copied.
*
* @return an array containing a copy of the vector elements.
*/
public double[] toArray() {
int dim = getDimension();
double[] values = new double[dim];
for (int i = 0; i < dim; i++) {
values[i] = getEntry(i);
}
return values;
}
/**
* Creates a unit vector pointing in the direction of this vector.
* The instance is not changed by this method.
*
* @return a unit vector pointing in direction of this vector.
* @throws MathArithmeticException if the norm is zero.
*/
public RealVector unitVector() throws MathArithmeticException {
final double norm = getNorm();
if (norm == 0) {
throw new MathArithmeticException(LocalizedFormats.ZERO_NORM);
}
return mapDivide(norm);
}
/**
* Converts this vector into a unit vector.
* The instance itself is changed by this method.
*
* @throws MathArithmeticException if the norm is zero.
*/
public void unitize() throws MathArithmeticException {
final double norm = getNorm();
if (norm == 0) {
throw new MathArithmeticException(LocalizedFormats.ZERO_NORM);
}
mapDivideToSelf(getNorm());
}
/**
* Create a sparse iterator over the vector, which may omit some entries.
* The ommitted entries are either exact zeroes (for dense implementations)
* or are the entries which are not stored (for real sparse vectors).
* No guarantees are made about order of iteration.
*
* Note: derived classes are required to return an {@link Iterator} that
* returns non-null {@link Entry} objects as long as {@link Iterator#hasNext()}
* returns {@code true}.
*
* @return a sparse iterator.
*/
public Iterator sparseIterator() {
return new SparseEntryIterator();
}
/**
* Generic dense iterator. Iteration is in increasing order
* of the vector index.
*
* Note: derived classes are required to return an {@link Iterator} that
* returns non-null {@link Entry} objects as long as {@link Iterator#hasNext()}
* returns {@code true}.
*
* @return a dense iterator.
*/
public Iterator iterator() {
final int dim = getDimension();
return new Iterator() {
/** Current index. */
private int i = 0;
/** Current entry. */
private Entry e = new Entry();
/** {@inheritDoc} */
public boolean hasNext() {
return i < dim;
}
/** {@inheritDoc} */
public Entry next() {
if (i < dim) {
e.setIndex(i++);
return e;
} else {
throw new NoSuchElementException();
}
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all circumstances.
*/
public void remove() throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
};
}
/**
* Acts as if implemented as:
*
* return copy().mapToSelf(function);
*
* Returns a new vector. Does not change instance data.
*
* @param function Function to apply to each entry.
* @return a new vector.
*/
public RealVector map(UnivariateFunction function) {
return copy().mapToSelf(function);
}
/**
* Acts as if it is implemented as:
*
* Entry e = null;
* for(Iterator it = iterator(); it.hasNext(); e = it.next()) {
* e.setValue(function.value(e.getValue()));
* }
*
* Entries of this vector are modified in-place by this method.
*
* @param function Function to apply to each entry.
* @return a reference to this vector.
*/
public RealVector mapToSelf(UnivariateFunction function) {
Iterator it = iterator();
while (it.hasNext()) {
final Entry e = it.next();
e.setValue(function.value(e.getValue()));
}
return this;
}
/**
* Returns a new vector representing {@code a * this + b * y}, the linear
* combination of {@code this} and {@code y}.
* Returns a new vector. Does not change instance data.
*
* @param a Coefficient of {@code this}.
* @param b Coefficient of {@code y}.
* @param y Vector with which {@code this} is linearly combined.
* @return a vector containing {@code a * this[i] + b * y[i]} for all
* {@code i}.
* @throws DimensionMismatchException if {@code y} is not the same size as
* {@code this} vector.
*/
public RealVector combine(double a, double b, RealVector y)
throws DimensionMismatchException {
return copy().combineToSelf(a, b, y);
}
/**
* Updates {@code this} with the linear combination of {@code this} and
* {@code y}.
*
* @param a Weight of {@code this}.
* @param b Weight of {@code y}.
* @param y Vector with which {@code this} is linearly combined.
* @return {@code this}, with components equal to
* {@code a * this[i] + b * y[i]} for all {@code i}.
* @throws DimensionMismatchException if {@code y} is not the same size as
* {@code this} vector.
*/
public RealVector combineToSelf(double a, double b, RealVector y)
throws DimensionMismatchException {
checkVectorDimensions(y);
for (int i = 0; i < getDimension(); i++) {
final double xi = getEntry(i);
final double yi = y.getEntry(i);
setEntry(i, a * xi + b * yi);
}
return this;
}
/**
* 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 RealVectorPreservingVisitor#end()}
* at the end of the walk
* @since 3.1
*/
public double walkInDefaultOrder(final RealVectorPreservingVisitor 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 RealVectorPreservingVisitor#end()}
* at the end of the walk
* @throws NumberIsTooSmallException if {@code end < start}.
* @throws OutOfRangeException if the indices are not valid.
* @since 3.1
*/
public double walkInDefaultOrder(final RealVectorPreservingVisitor 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 RealVectorPreservingVisitor#end()}
* at the end of the walk
* @since 3.1
*/
public double walkInOptimizedOrder(final RealVectorPreservingVisitor 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 RealVectorPreservingVisitor#end()}
* at the end of the walk
* @throws NumberIsTooSmallException if {@code end < start}.
* @throws OutOfRangeException if the indices are not valid.
* @since 3.1
*/
public double walkInOptimizedOrder(final RealVectorPreservingVisitor 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 RealVectorChangingVisitor#end()}
* at the end of the walk
* @since 3.1
*/
public double walkInDefaultOrder(final RealVectorChangingVisitor 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 RealVectorChangingVisitor#end()}
* at the end of the walk
* @throws NumberIsTooSmallException if {@code end < start}.
* @throws OutOfRangeException if the indices are not valid.
* @since 3.1
*/
public double walkInDefaultOrder(final RealVectorChangingVisitor 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 RealVectorChangingVisitor#end()}
* at the end of the walk
* @since 3.1
*/
public double walkInOptimizedOrder(final RealVectorChangingVisitor 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 RealVectorChangingVisitor#end()}
* at the end of the walk
* @throws NumberIsTooSmallException if {@code end < start}.
* @throws OutOfRangeException if the indices are not valid.
* @since 3.1
*/
public double walkInOptimizedOrder(final RealVectorChangingVisitor visitor,
final int start, final int end)
throws NumberIsTooSmallException, OutOfRangeException {
return walkInDefaultOrder(visitor, start, end);
}
/** An entry in the vector. */
protected class Entry {
/** Index of this entry. */
private int index;
/** Simple constructor. */
public Entry() {
setIndex(0);
}
/**
* Get the value of the entry.
*
* @return the value of the entry.
*/
public double getValue() {
return getEntry(getIndex());
}
/**
* Set the value of the entry.
*
* @param value New value for the entry.
*/
public void setValue(double value) {
setEntry(getIndex(), value);
}
/**
* Get the index of the entry.
*
* @return the index of the entry.
*/
public int getIndex() {
return index;
}
/**
* Set the index of the entry.
*
* @param index New index for the entry.
*/
public void setIndex(int index) {
this.index = index;
}
}
/**
*
* Test for the equality of two real vectors. If all coordinates of two real
* vectors are exactly the same, and none are {@code NaN}, the two real
* vectors are considered to be equal. {@code NaN} coordinates are
* considered to affect globally the vector and be equals to each other -
* i.e, if either (or all) coordinates of the real vector are equal to
* {@code NaN}, the real vector is equal to a vector with all {@code NaN}
* coordinates.
*
*
* This method must be overriden by concrete subclasses of
* {@link RealVector} (the current implementation throws an exception).
*
*
* @param other Object to test for equality.
* @return {@code true} if two vector objects are equal, {@code false} if
* {@code other} is null, not an instance of {@code RealVector}, or
* not equal to this {@code RealVector} instance.
* @throws MathUnsupportedOperationException if this method is not
* overridden.
*/
@Override
public boolean equals(Object other)
throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
/**
* {@inheritDoc}. This method must be overriden by concrete
* subclasses of {@link RealVector} (current implementation throws an
* exception).
*
* @throws MathUnsupportedOperationException if this method is not
* overridden.
*/
@Override
public int hashCode() throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
/**
* This class should rarely be used, but is here to provide
* a default implementation of sparseIterator(), which is implemented
* by walking over the entries, skipping those that are zero.
*
* Concrete subclasses which are SparseVector implementations should
* make their own sparse iterator, rather than using this one.
*
* This implementation might be useful for ArrayRealVector, when expensive
* operations which preserve the default value are to be done on the entries,
* and the fraction of non-default values is small (i.e. someone took a
* SparseVector, and passed it into the copy-constructor of ArrayRealVector)
*/
protected class SparseEntryIterator implements Iterator {
/** Dimension of the vector. */
private final int dim;
/** Last entry returned by {@link #next()}. */
private Entry current;
/** Next entry for {@link #next()} to return. */
private Entry next;
/** Simple constructor. */
protected SparseEntryIterator() {
dim = getDimension();
current = new Entry();
next = new Entry();
if (next.getValue() == 0) {
advance(next);
}
}
/**
* Advance an entry up to the next nonzero one.
*
* @param e entry to advance.
*/
protected void advance(Entry e) {
if (e == null) {
return;
}
do {
e.setIndex(e.getIndex() + 1);
} while (e.getIndex() < dim && e.getValue() == 0);
if (e.getIndex() >= dim) {
e.setIndex(-1);
}
}
/** {@inheritDoc} */
public boolean hasNext() {
return next.getIndex() >= 0;
}
/** {@inheritDoc} */
public Entry next() {
int index = next.getIndex();
if (index < 0) {
throw new NoSuchElementException();
}
current.setIndex(index);
advance(next);
return current;
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all circumstances.
*/
public void remove() throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
}
/**
* Returns an unmodifiable view of the specified vector.
* The returned vector has read-only access. An attempt to modify it will
* result in a {@link MathUnsupportedOperationException}. However, the
* returned vector is not immutable, since any modification of
* {@code v} will also change the returned view.
* For example, in the following piece of code
*
* RealVector v = new ArrayRealVector(2);
* RealVector w = RealVector.unmodifiableRealVector(v);
* v.setEntry(0, 1.2);
* v.setEntry(1, -3.4);
*
* the changes will be seen in the {@code w} view of {@code v}.
*
* @param v Vector for which an unmodifiable view is to be returned.
* @return an unmodifiable view of {@code v}.
*/
public static RealVector unmodifiableRealVector(final RealVector v) {
/**
* This anonymous class is an implementation of {@link RealVector}
* with read-only access.
* It wraps any {@link RealVector}, and exposes all methods which
* do not modify it. Invoking methods which should normally result
* in the modification of the calling {@link RealVector} results in
* a {@link MathUnsupportedOperationException}. It should be noted
* that {@link UnmodifiableVector} is not immutable.
*/
return new RealVector() {
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all circumstances.
*/
@Override
public RealVector mapToSelf(UnivariateFunction function)
throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
/** {@inheritDoc} */
@Override
public RealVector map(UnivariateFunction function) {
return v.map(function);
}
/** {@inheritDoc} */
@Override
public Iterator iterator() {
final Iterator i = v.iterator();
return new Iterator() {
/** The current entry. */
private final UnmodifiableEntry e = new UnmodifiableEntry();
/** {@inheritDoc} */
public boolean hasNext() {
return i.hasNext();
}
/** {@inheritDoc} */
public Entry next() {
e.setIndex(i.next().getIndex());
return e;
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all
* circumstances.
*/
public void remove() throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
};
}
/** {@inheritDoc} */
@Override
public Iterator sparseIterator() {
final Iterator i = v.sparseIterator();
return new Iterator() {
/** The current entry. */
private final UnmodifiableEntry e = new UnmodifiableEntry();
/** {@inheritDoc} */
public boolean hasNext() {
return i.hasNext();
}
/** {@inheritDoc} */
public Entry next() {
e.setIndex(i.next().getIndex());
return e;
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all
* circumstances.
*/
public void remove()
throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
};
}
/** {@inheritDoc} */
@Override
public RealVector copy() {
return v.copy();
}
/** {@inheritDoc} */
@Override
public RealVector add(RealVector w)
throws DimensionMismatchException {
return v.add(w);
}
/** {@inheritDoc} */
@Override
public RealVector subtract(RealVector w)
throws DimensionMismatchException {
return v.subtract(w);
}
/** {@inheritDoc} */
@Override
public RealVector mapAdd(double d) {
return v.mapAdd(d);
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all
* circumstances.
*/
@Override
public RealVector mapAddToSelf(double d)
throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
/** {@inheritDoc} */
@Override
public RealVector mapSubtract(double d) {
return v.mapSubtract(d);
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all
* circumstances.
*/
@Override
public RealVector mapSubtractToSelf(double d)
throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
/** {@inheritDoc} */
@Override
public RealVector mapMultiply(double d) {
return v.mapMultiply(d);
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all
* circumstances.
*/
@Override
public RealVector mapMultiplyToSelf(double d)
throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
/** {@inheritDoc} */
@Override
public RealVector mapDivide(double d) {
return v.mapDivide(d);
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all
* circumstances.
*/
@Override
public RealVector mapDivideToSelf(double d)
throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
/** {@inheritDoc} */
@Override
public RealVector ebeMultiply(RealVector w)
throws DimensionMismatchException {
return v.ebeMultiply(w);
}
/** {@inheritDoc} */
@Override
public RealVector ebeDivide(RealVector w)
throws DimensionMismatchException {
return v.ebeDivide(w);
}
/** {@inheritDoc} */
@Override
public double dotProduct(RealVector w)
throws DimensionMismatchException {
return v.dotProduct(w);
}
/** {@inheritDoc} */
@Override
public double cosine(RealVector w)
throws DimensionMismatchException, MathArithmeticException {
return v.cosine(w);
}
/** {@inheritDoc} */
@Override
public double getNorm() {
return v.getNorm();
}
/** {@inheritDoc} */
@Override
public double getL1Norm() {
return v.getL1Norm();
}
/** {@inheritDoc} */
@Override
public double getLInfNorm() {
return v.getLInfNorm();
}
/** {@inheritDoc} */
@Override
public double getDistance(RealVector w)
throws DimensionMismatchException {
return v.getDistance(w);
}
/** {@inheritDoc} */
@Override
public double getL1Distance(RealVector w)
throws DimensionMismatchException {
return v.getL1Distance(w);
}
/** {@inheritDoc} */
@Override
public double getLInfDistance(RealVector w)
throws DimensionMismatchException {
return v.getLInfDistance(w);
}
/** {@inheritDoc} */
@Override
public RealVector unitVector() throws MathArithmeticException {
return v.unitVector();
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all
* circumstances.
*/
@Override
public void unitize() throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
/** {@inheritDoc} */
@Override
public RealMatrix outerProduct(RealVector w) {
return v.outerProduct(w);
}
/** {@inheritDoc} */
@Override
public double getEntry(int index) throws OutOfRangeException {
return v.getEntry(index);
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all
* circumstances.
*/
@Override
public void setEntry(int index, double value)
throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all
* circumstances.
*/
@Override
public void addToEntry(int index, double value)
throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
/** {@inheritDoc} */
@Override
public int getDimension() {
return v.getDimension();
}
/** {@inheritDoc} */
@Override
public RealVector append(RealVector w) {
return v.append(w);
}
/** {@inheritDoc} */
@Override
public RealVector append(double d) {
return v.append(d);
}
/** {@inheritDoc} */
@Override
public RealVector getSubVector(int index, int n)
throws OutOfRangeException, NotPositiveException {
return v.getSubVector(index, n);
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all
* circumstances.
*/
@Override
public void setSubVector(int index, RealVector w)
throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all
* circumstances.
*/
@Override
public void set(double value)
throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
/** {@inheritDoc} */
@Override
public double[] toArray() {
return v.toArray();
}
/** {@inheritDoc} */
@Override
public boolean isNaN() {
return v.isNaN();
}
/** {@inheritDoc} */
@Override
public boolean isInfinite() {
return v.isInfinite();
}
/** {@inheritDoc} */
@Override
public RealVector combine(double a, double b, RealVector y)
throws DimensionMismatchException {
return v.combine(a, b, y);
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all
* circumstances.
*/
@Override
public RealVector combineToSelf(double a, double b, RealVector y)
throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
/** An entry in the vector. */
class UnmodifiableEntry extends Entry {
/** {@inheritDoc} */
@Override
public double getValue() {
return v.getEntry(getIndex());
}
/**
* {@inheritDoc}
*
* @throws MathUnsupportedOperationException in all
* circumstances.
*/
@Override
public void setValue(double value)
throws MathUnsupportedOperationException {
throw new MathUnsupportedOperationException();
}
}
};
}
}
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