weka.core

## Class AlgVector

- java.lang.Object
- - weka.core.AlgVector

- All Implemented Interfaces:
    java.io.Serializable, java.lang.Cloneable, RevisionHandler

      public class AlgVector
      extends java.lang.Object
      implements java.lang.Cloneable, java.io.Serializable, RevisionHandler

  Class for performing operations on an algebraic vector of floating-point values.
  Version:
    $Revision: 8034 $
  Author:
    Gabi Schmidberger (gabi@cs.waikato.ac.nz)
  See Also:
    Serialized Form

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `AlgVector(double[] array)` Constructs a vector using a given array.
    `AlgVector(Instance instance)` Constructs a vector using an instance.
    `AlgVector(Instances format, java.util.Random random)` Constructs a vector using a given data format.
    `AlgVector(int n)` Constructs a vector and initializes it with default values.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `AlgVector` | `add(AlgVector other)` Returns the sum of this vector with another.
    `void` | `changeLength(double len)` Changes the length of a vector.
    `java.lang.Object` | `clone()` Creates and returns a clone of this object.
    `double` | `dotMultiply(AlgVector b)` Returns the inner (or dot) product of two vectors
    `Instance` | `getAsInstance(Instances model, java.util.Random random)` Gets the elements of the vector as an instance.
    `double` | `getElement(int index)` Returns the value of a cell in the matrix.
    `double[]` | `getElements()` Gets the elements of the vector and returns them as double array.
    `java.lang.String` | `getRevision()` Returns the revision string.
    `static void` | `main(java.lang.String[] args)` Main method for testing this class, can take an ARFF file as first argument.
    `double` | `norm()` Returns the norm of the vector
    `void` | `normVector()` Norms this vector to length 1.0
    `int` | `numElements()` Returns the number of elements in the vector.
    `void` | `scalarMultiply(double s)` Computes the scalar product of this vector with a scalar
    `void` | `setElement(int index, double value)` Sets an element of the matrix to the given value.
    `void` | `setElements(double[] elements)` Sets the elements of the vector to values of the given array.
    `AlgVector` | `substract(AlgVector other)` Returns the difference of this vector minus another.
    `java.lang.String` | `toString()` Converts a vector to a string

    - ### Methods inherited from class java.lang.Object

      `equals, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- - ### Constructor Detail

    - #### AlgVector

          public AlgVector(int n)

      Constructs a vector and initializes it with default values.
      Parameters:
        `n` - the number of elements

    - #### AlgVector

          public AlgVector(double[] array)

      Constructs a vector using a given array.
      Parameters:
        `array` - the values of the matrix

    - #### AlgVector

          public AlgVector(Instances format,
                   java.util.Random random)
                    throws java.lang.Exception

      Constructs a vector using a given data format. The vector has an element for each numerical attribute. The other attributes (nominal, string) are ignored. Random is used to initialize the attributes.
      Parameters:
        `format` - the data format to use
        `random` - for initializing the attributes
      Throws:
        `java.lang.Exception` - if something goes wrong

    - #### AlgVector

          public AlgVector(Instance instance)
                    throws java.lang.Exception

      Constructs a vector using an instance. The vector has an element for each numerical attribute. The other attributes (nominal, string) are ignored.
      Parameters:
        `instance` - with numeric attributes, that AlgVector gets build from
      Throws:
        `java.lang.Exception` - if instance doesn't have access to the data format or no numeric attributes in the data

  - ### Method Detail

    - #### clone

          public java.lang.Object clone()
                                 throws java.lang.CloneNotSupportedException

      Creates and returns a clone of this object.
      Overrides:
        `clone` in class `java.lang.Object`
      Returns:
        a clone of this instance.
      Throws:
        `java.lang.CloneNotSupportedException` - if an error occurs

    - #### getElement

          public final double getElement(int index)

      Returns the value of a cell in the matrix.
      Parameters:
        `index` - the row's index
      Returns:
        the value of the cell of the vector

    - #### numElements

          public final int numElements()

      Returns the number of elements in the vector.
      Returns:
        the number of rows

    - #### setElement

          public final void setElement(int index,
                        double value)

      Sets an element of the matrix to the given value.
      Parameters:
        `index` - the elements index
        `value` - the new value

    - #### setElements

          public final void setElements(double[] elements)

      Sets the elements of the vector to values of the given array. Performs a deep copy.
      Parameters:
        `elements` - an array of doubles

    - #### getElements

          public double[] getElements()

      Gets the elements of the vector and returns them as double array.
      Returns:
        an array of doubles

    - #### getAsInstance

          public Instance getAsInstance(Instances model,
                               java.util.Random random)
                                 throws java.lang.Exception

      Gets the elements of the vector as an instance. !! NON-numeric data is ignored sofar
      Parameters:
        `model` - the dataset structure to fit the data to
        `random` - in case of nominal values a random label is taken
      Returns:
        an array of doubles
      Throws:
        `java.lang.Exception` - if length of vector is not number of numerical attributes

    - #### add

          public final AlgVector add(AlgVector other)

      Returns the sum of this vector with another.
      Parameters:
        `other` - the vector to add
      Returns:
        a vector containing the sum.

    - #### substract

          public final AlgVector substract(AlgVector other)

      Returns the difference of this vector minus another.
      Parameters:
        `other` - the vector to subtract
      Returns:
        a vector containing the difference vector.

    - #### dotMultiply

          public final double dotMultiply(AlgVector b)

      Returns the inner (or dot) product of two vectors
      Parameters:
        `b` - the multiplication matrix
      Returns:
        the double representing the dot product

    - #### scalarMultiply

          public final void scalarMultiply(double s)

      Computes the scalar product of this vector with a scalar
      Parameters:
        `s` - the scalar

    - #### changeLength

          public void changeLength(double len)

      Changes the length of a vector.
      Parameters:
        `len` - the new length of the vector

    - #### norm

          public double norm()

      Returns the norm of the vector
      Returns:
        the norm of the vector

    - #### normVector

          public final void normVector()

      Norms this vector to length 1.0

    - #### toString

          public java.lang.String toString()

      Converts a vector to a string
      Overrides:
        `toString` in class `java.lang.Object`
      Returns:
        the converted string

    - #### getRevision

          public java.lang.String getRevision()

      Returns the revision string.
      Specified by:
        `getRevision` in interface `RevisionHandler`
      Returns:
        the revision

    - #### main

          public static void main(java.lang.String[] args)
                           throws java.lang.Exception

      Main method for testing this class, can take an ARFF file as first argument.
      Parameters:
        `args` - commandline options
      Throws:
        `java.lang.Exception` - if something goes wrong in testing