Package org.apache.commons.math3.linear

Class OpenMapRealVector

java.lang.Object
org.apache.commons.math3.linear.RealVector
org.apache.commons.math3.linear.SparseRealVector
org.apache.commons.math3.linear.OpenMapRealVector
All Implemented Interfaces:
Serializable
public class OpenMapRealVector extends SparseRealVector implements Serializable
This class implements the RealVector interface with a OpenIntToDoubleHashMap backing store.

Caveat: This implementation assumes that, for any x, the equality x * 0d == 0d holds. But it is is not true for NaN. Moreover, zero entries will lose their sign. Some operations (that involve NaN and/or infinities) may thus give incorrect results, like multiplications, divisions or functions mapping.

Since:
2.0
See Also:

  • Field Details

    • DEFAULT_ZERO_TOLERANCE

      public static final double DEFAULT_ZERO_TOLERANCE
      Default Tolerance for having a value considered zero.
      See Also:

  • Constructor Details

    • OpenMapRealVector

      public OpenMapRealVector()
      Build a 0-length vector. Zero-length vectors may be used to initialized construction of vectors by data gathering. We start with zero-length and use either the OpenMapRealVector(OpenMapRealVector, int) constructor or one of the append method (append(double), append(RealVector)) to gather data into this vector.

    • OpenMapRealVector

      public OpenMapRealVector(int dimension)
      Construct a vector of zeroes.
      Parameters:
      dimension - Size of the vector.

    • OpenMapRealVector

      public OpenMapRealVector(int dimension, double epsilon)
      Construct a vector of zeroes, specifying zero tolerance.
      Parameters:
      dimension - Size of the vector.
      epsilon - Tolerance below which a value considered zero.

    • OpenMapRealVector

      protected OpenMapRealVector(OpenMapRealVector v, int resize)
      Build a resized vector, for use with append.
      Parameters:
      v - Original vector.
      resize - Amount to add.

    • OpenMapRealVector

      public OpenMapRealVector(int dimension, int expectedSize)
      Build a vector with known the sparseness (for advanced use only).
      Parameters:
      dimension - Size of the vector.
      expectedSize - The expected number of non-zero entries.

    • OpenMapRealVector

      public OpenMapRealVector(int dimension, int expectedSize, double epsilon)
      Build a vector with known the sparseness and zero tolerance setting (for advanced use only).
      Parameters:
      dimension - Size of the vector.
      expectedSize - Expected number of non-zero entries.
      epsilon - Tolerance below which a value is considered zero.

    • OpenMapRealVector

      public OpenMapRealVector(double[] values)
      Create from an array. Only non-zero entries will be stored.
      Parameters:
      values - Set of values to create from.

    • OpenMapRealVector

      public OpenMapRealVector(double[] values, double epsilon)
      Create from an array, specifying zero tolerance. Only non-zero entries will be stored.
      Parameters:
      values - Set of values to create from.
      epsilon - Tolerance below which a value is considered zero.

    • OpenMapRealVector

      public OpenMapRealVector(Double[] values)
      Create from an array. Only non-zero entries will be stored.
      Parameters:
      values - The set of values to create from

    • OpenMapRealVector

      public OpenMapRealVector(Double[] values, double epsilon)
      Create from an array. Only non-zero entries will be stored.
      Parameters:
      values - Set of values to create from.
      epsilon - Tolerance below which a value is considered zero.

    • OpenMapRealVector

      public OpenMapRealVector(OpenMapRealVector v)
      Copy constructor.
      Parameters:
      v - Instance to copy from.

    • OpenMapRealVector

      public OpenMapRealVector(RealVector v)
      Generic copy constructor.
      Parameters:
      v - Instance to copy from.

  • Method Details

    • isDefaultValue

      protected boolean isDefaultValue(double value)
      Determine if this value is within epsilon of zero.
      Parameters:
      value - Value to test
      Returns:
      true if this value is within epsilon to zero, false otherwise.
      Since:
      2.1

    • add

      public RealVector add(RealVector v) throws DimensionMismatchException
      Compute the sum of this vector and v. Returns a new vector. Does not change instance data.
      Overrides:
      add in class RealVector
      Parameters:
      v - Vector to be added.
      Returns:
      this + v.
      Throws:
      DimensionMismatchException - if v is not the same size as this vector.

    • add

      public OpenMapRealVector add(OpenMapRealVector v) throws DimensionMismatchException
      Optimized method to add two OpenMapRealVectors. It copies the larger vector, then iterates over the smaller.
      Parameters:
      v - Vector to add.
      Returns:
      the sum of this and v.
      Throws:
      DimensionMismatchException - if the dimensions do not match.

    • append

      public OpenMapRealVector append(OpenMapRealVector v)
      Optimized method to append a OpenMapRealVector.
      Parameters:
      v - vector to append
      Returns:
      The result of appending v to self

    • append

      public OpenMapRealVector append(RealVector v)
      Construct a new vector by appending a vector to this vector.
      Specified by:
      append in class RealVector
      Parameters:
      v - vector to append to this one.
      Returns:
      a new vector.

    • append

      public OpenMapRealVector append(double d)
      Construct a new vector by appending a double to this vector.
      Specified by:
      append in class RealVector
      Parameters:
      d - double to append.
      Returns:
      a new vector.

    • copy

      public OpenMapRealVector copy()
      Returns a (deep) copy of this vector.
      Specified by:
      copy in class RealVector
      Returns:
      a vector copy.
      Since:
      2.1

    • dotProduct

      @Deprecated public double dotProduct(OpenMapRealVector v) throws DimensionMismatchException
      Deprecated.
      as of 3.1 (to be removed in 4.0). The computation is performed by the parent class. The method must be kept to maintain backwards compatibility.
      Computes the dot product. Note that the computation is now performed in the parent class: no performance improvement is to be expected from this overloaded method. The previous implementation was buggy and cannot be easily fixed (see MATH-795).
      Parameters:
      v - Vector.
      Returns:
      the dot product of this vector with v.
      Throws:
      DimensionMismatchException - if v is not the same size as this vector.

    • ebeDivide

      public OpenMapRealVector ebeDivide(RealVector v) throws DimensionMismatchException
      Element-by-element division.
      Specified by:
      ebeDivide in class RealVector
      Parameters:
      v - Vector by which instance elements must be divided.
      Returns:
      a vector containing this[i] / v[i] for all i.
      Throws:
      DimensionMismatchException - if v is not the same size as this vector.

    • ebeMultiply

      public OpenMapRealVector ebeMultiply(RealVector v) throws DimensionMismatchException
      Element-by-element multiplication.
      Specified by:
      ebeMultiply in class RealVector
      Parameters:
      v - Vector by which instance elements must be multiplied
      Returns:
      a vector containing this[i] * v[i] for all i.
      Throws:
      DimensionMismatchException - if v is not the same size as this vector.

    • getSubVector

      public OpenMapRealVector getSubVector(int index, int n) throws NotPositiveException, OutOfRangeException
      Get a subvector from consecutive elements.
      Specified by:
      getSubVector in class RealVector
      Parameters:
      index - index of first element.
      n - number of elements to be retrieved.
      Returns:
      a vector containing n elements.
      Throws:
      NotPositiveException - if the number of elements is not positive.
      OutOfRangeException - if the index is not valid.

    • getDimension

      public int getDimension()
      Returns the size of the vector.
      Specified by:
      getDimension in class RealVector
      Returns:
      the size of this vector.

    • getDistance

      public double getDistance(OpenMapRealVector v) throws DimensionMismatchException
      Optimized method to compute distance.
      Parameters:
      v - Vector to compute distance to.
      Returns:
      the distance from this and v.
      Throws:
      DimensionMismatchException - if the dimensions do not match.

    • getDistance

      public double getDistance(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.

      Overrides:
      getDistance in class RealVector
      Parameters:
      v - Vector to which distance is requested.
      Returns:
      the distance between two vectors.
      Throws:
      DimensionMismatchException - if v is not the same size as this vector.
      See Also:

    • getEntry

      public double getEntry(int index) throws OutOfRangeException
      Return the entry at the specified index.
      Specified by:
      getEntry in class RealVector
      Parameters:
      index - Index location of entry to be fetched.
      Returns:
      the vector entry at index.
      Throws:
      OutOfRangeException - if the index is not valid.
      See Also:

    • getL1Distance

      public double getL1Distance(OpenMapRealVector v) throws DimensionMismatchException
      Distance between two vectors. This method computes the distance consistent with L1 norm, i.e. the sum of the absolute values of elements differences.
      Parameters:
      v - Vector to which distance is requested.
      Returns:
      distance between this vector and v.
      Throws:
      DimensionMismatchException - if the dimensions do not match.

    • getL1Distance

      public double getL1Distance(RealVector v) throws DimensionMismatchException
      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.

      Overrides:
      getL1Distance in class RealVector
      Parameters:
      v - Vector to which distance is requested.
      Returns:
      the distance between two vectors.
      Throws:
      DimensionMismatchException - if v is not the same size as this vector.

    • getLInfDistance

      public double getLInfDistance(RealVector v) throws DimensionMismatchException
      Distance between two vectors.

      This method computes the distance consistent with L∞ norm, i.e. the max of the absolute values of element differences.

      Overrides:
      getLInfDistance in class RealVector
      Parameters:
      v - Vector to which distance is requested.
      Returns:
      the distance between two vectors.
      Throws:
      DimensionMismatchException - if v is not the same size as this vector.
      See Also:

    • isInfinite

      public boolean isInfinite()
      Check whether any coordinate of this vector is infinite and none are NaN.
      Specified by:
      isInfinite in class RealVector
      Returns:
      true if any coordinate of this vector is infinite and none are NaN, false otherwise.

    • isNaN

      public boolean isNaN()
      Check whether any coordinate of this vector is NaN.
      Specified by:
      isNaN in class RealVector
      Returns:
      true if any coordinate of this vector is NaN, false otherwise.

    • mapAdd

      public OpenMapRealVector mapAdd(double d)
      Add a value to each entry. Returns a new vector. Does not change instance data.
      Overrides:
      mapAdd in class RealVector
      Parameters:
      d - Value to be added to each entry.
      Returns:
      this + d.

    • mapAddToSelf

      public OpenMapRealVector mapAddToSelf(double d)
      Add a value to each entry. The instance is changed in-place.
      Overrides:
      mapAddToSelf in class RealVector
      Parameters:
      d - Value to be added to each entry.
      Returns:
      this.

    • setEntry

      public void setEntry(int index, double value) throws OutOfRangeException
      Set a single element.
      Specified by:
      setEntry in class RealVector
      Parameters:
      index - element index.
      value - new value for the element.
      Throws:
      OutOfRangeException - if the index is not valid.
      See Also:

    • setSubVector

      public void setSubVector(int index, RealVector v) throws OutOfRangeException
      Set a sequence of consecutive elements.
      Specified by:
      setSubVector in class RealVector
      Parameters:
      index - index of first element to be set.
      v - vector containing the values to set.
      Throws:
      OutOfRangeException - if the index is not valid.

    • set

      public void set(double value)
      Set all elements to a single value.
      Overrides:
      set in class RealVector
      Parameters:
      value - Single value to set for all elements.

    • subtract

      public OpenMapRealVector subtract(OpenMapRealVector v) throws DimensionMismatchException
      Optimized method to subtract OpenMapRealVectors.
      Parameters:
      v - Vector to subtract from this.
      Returns:
      the difference of this and v.
      Throws:
      DimensionMismatchException - if the dimensions do not match.

    • subtract

      public RealVector subtract(RealVector v) throws DimensionMismatchException
      Subtract v from this vector. Returns a new vector. Does not change instance data.
      Overrides:
      subtract in class RealVector
      Parameters:
      v - Vector to be subtracted.
      Returns:
      this - v.
      Throws:
      DimensionMismatchException - if v is not the same size as this vector.

    • unitVector

      public OpenMapRealVector unitVector() throws MathArithmeticException
      Creates a unit vector pointing in the direction of this vector. The instance is not changed by this method.
      Overrides:
      unitVector in class RealVector
      Returns:
      a unit vector pointing in direction of this vector.
      Throws:
      MathArithmeticException - if the norm is zero.

    • unitize

      public void unitize() throws MathArithmeticException
      Converts this vector into a unit vector. The instance itself is changed by this method.
      Overrides:
      unitize in class RealVector
      Throws:
      MathArithmeticException - if the norm is zero.

    • toArray

      public double[] toArray()
      Convert the vector to an array of doubles. The array is independent from this vector data: the elements are copied.
      Overrides:
      toArray in class RealVector
      Returns:
      an array containing a copy of the vector elements.

    • hashCode

      public int hashCode()
      . This method must be overriden by concrete subclasses of RealVector (current implementation throws an exception). Implementation Note: This works on exact values, and as a result it is possible for a.subtract(b) to be the zero vector, while a.hashCode() != b.hashCode().
      Overrides:
      hashCode in class RealVector

    • equals

      public boolean equals(Object obj)

      Test for the equality of two real vectors. If all coordinates of two real vectors are exactly the same, and none are NaN, the two real vectors are considered to be equal. 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 NaN, the real vector is equal to a vector with all NaN coordinates.

      This method must be overriden by concrete subclasses of RealVector (the current implementation throws an exception).

      Implementation Note: This performs an exact comparison, and as a result it is possible for a.subtract(b} to be the zero vector, while a.equals(b) == false.
      Overrides:
      equals in class RealVector
      Parameters:
      obj - Object to test for equality.
      Returns:
      true if two vector objects are equal, false if other is null, not an instance of RealVector, or not equal to this RealVector instance.

    • getSparsity

      public double getSparsity()
      Returns:
      the percentage of none zero elements as a decimal percent.
      Since:
      2.2

    • sparseIterator

      public Iterator<RealVector.Entry> sparseIterator()
      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 Iterator that returns non-null RealVector.Entry objects as long as Iterator.hasNext() returns true.

      Overrides:
      sparseIterator in class RealVector
      Returns:
      a sparse iterator.