Package weka.core

Interface Instance

All Superinterfaces:
Copyable
All Known Implementing Classes:
AbstractInstance, BinarySparseInstance, DenseInstance, SparseInstance
public interface Instance extends Copyable
Interface representing an instance. All values (numeric, date, nominal, string or relational) are internally stored as floating-point numbers in the original concrete class implementations (now called DenseInstance.java and SparseInstance.java), and the methods in this interface reflect this. If an attribute is nominal (or a string or relational), the stored value is the index of the corresponding nominal (or string or relational) value in the attribute's definition. We have chosen this approach in favor of a more elegant object-oriented approach because it is much faster.

Typical usage (code from the main() method of this class):

...
// Create empty instance with three attribute values
Instance inst = new DenseInstance(3);

// Set instance's values for the attributes "length", "weight", and "position"
inst.setValue(length, 5.3);
inst.setValue(weight, 300);
inst.setValue(position, "first");

// Set instance's dataset to be the dataset "race"
inst.setDataset(race);

// Print the instance
System.out.println("The instance: " + inst);
...

All methods that change an instance's attribute values must be safe, ie. a change of an instance's attribute values must not affect any other instances.

Version:
$Revision: 15069 $
Author:
Eibe Frank (eibe@cs.waikato.ac.nz)

  • Method Summary

    Modifier and Type
    Method
    Description
    Attribute
    attribute(int index)
    Returns the attribute with the given index.
    Attribute
    attributeSparse(int indexOfIndex)
    Returns the attribute with the given index in the sparse representation.
    Attribute
    classAttribute()
    Returns class attribute.
    int
    classIndex()
    Returns the class attribute's index.
    boolean
    classIsMissing()
    Tests if an instance's class is missing.
    double
    classValue()
    Returns an instance's class value as a floating-point number.
    Instance
    copy(double[] values)
    Copies the instance but fills up its values based on the given array of doubles.
    Instances
    dataset()
    Returns the dataset this instance has access to.
    void
    deleteAttributeAt(int position)
    Deletes an attribute at the given position (0 to numAttributes() - 1).
    Enumeration<Attribute>
    enumerateAttributes()
    Returns an enumeration of all the attributes.
    boolean
    equalHeaders(Instance inst)
    Tests if the headers of two instances are equivalent.
    String
    equalHeadersMsg(Instance inst)
    Checks if the headers of two instances are equivalent.
    boolean
    hasMissingValue()
    Tests whether an instance has a missing value.
    int
    index(int position)
    Returns the index of the attribute stored at the given position in the sparse representation.
    void
    insertAttributeAt(int position)
    Inserts an attribute at the given position (0 to numAttributes()).
    boolean
    isMissing(int attIndex)
    Tests if a specific value is "missing".
    boolean
    isMissing(Attribute att)
    Tests if a specific value is "missing".
    boolean
    isMissingSparse(int indexOfIndex)
    Tests if a specific value is "missing" in the sparse representation.
    Instance
    mergeInstance(Instance inst)
    Merges this instance with the given instance and returns the result.
    int
    numAttributes()
    Returns the number of attributes.
    int
    numClasses()
    Returns the number of class labels.
    int
    numValues()
    Returns the number of values present in a sparse representation.
    Instances
    relationalValue(int attIndex)
    Returns the relational value of a relational attribute.
    Instances
    relationalValue(Attribute att)
    Returns the relational value of a relational attribute.
    void
    replaceMissingValues(double[] array)
    Replaces all missing values in the instance with the values contained in the given array.
    void
    setClassMissing()
    Sets the class value of an instance to be "missing".
    void
    setClassValue(double value)
    Sets the class value of an instance to the given value (internal floating-point format).
    void
    setClassValue(String value)
    Sets the class value of an instance to the given value.
    void
    setDataset(Instances instances)
    Sets the reference to the dataset.
    void
    setMissing(int attIndex)
    Sets a specific value to be "missing".
    void
    setMissing(Attribute att)
    Sets a specific value to be "missing".
    void
    setValue(int attIndex, double value)
    Sets a specific value in the instance to the given value (internal floating-point format).
    void
    setValue(int attIndex, String value)
    Sets a value of a nominal or string attribute to the given value.
    void
    setValue(Attribute att, double value)
    Sets a specific value in the instance to the given value (internal floating-point format).
    void
    setValue(Attribute att, String value)
    Sets a value of an nominal or string attribute to the given value.
    void
    setValueSparse(int indexOfIndex, double value)
    Sets a specific value in the instance to the given value (internal floating-point format), given an index into the sparse representation.
    void
    setWeight(double weight)
    Sets the weight of an instance.
    String
    stringValue(int attIndex)
    Returns the value of a nominal, string, date, or relational attribute for the instance as a string.
    String
    stringValue(Attribute att)
    Returns the value of a nominal, string, date, or relational attribute for the instance as a string.
    double[]
    toDoubleArray()
    Returns the values of each attribute as an array of doubles.
    String
    toString(int attIndex)
    Returns the description of one value of the instance as a string.
    String
    toString(int attIndex, int afterDecimalPoint)
    Returns the description of one value of the instance as a string.
    String
    toString(Attribute att)
    Returns the description of one value of the instance as a string.
    String
    toString(Attribute att, int afterDecimalPoint)
    Returns the description of one value of the instance as a string.
    String
    toStringMaxDecimalDigits(int afterDecimalPoint)
    Returns the description of one instance with any numeric values printed at the supplied maximum number of decimal places.
    String
    toStringNoWeight()
    Returns the description of one instance (without weight appended).
    String
    toStringNoWeight(int afterDecimalPoint)
    Returns the description of one instance (without weight appended).
    double
    value(int attIndex)
    Returns an instance's attribute value in internal format.
    double
    value(Attribute att)
    Returns an instance's attribute value in internal format.
    double
    valueSparse(int indexOfIndex)
    Returns an instance's attribute value in internal format, given an index in the sparse representation.
    double
    weight()
    Returns the instance's weight.

    Methods inherited from interface weka.core.Copyable

    copy

  • Method Details

    • attribute

      Attribute attribute(int index)
      Returns the attribute with the given index.
      Parameters:
      index - the attribute's index
      Returns:
      the attribute at the given position
      Throws:
      UnassignedDatasetException - if instance doesn't have access to a dataset

    • attributeSparse

      Attribute attributeSparse(int indexOfIndex)
      Returns the attribute with the given index in the sparse representation. Same as attribute(int) for a DenseInstance.
      Parameters:
      indexOfIndex - the index of the attribute's index
      Returns:
      the attribute at the given position
      Throws:
      UnassignedDatasetException - if instance doesn't have access to a dataset

    • classAttribute

      Attribute classAttribute()
      Returns class attribute.
      Returns:
      the class attribute
      Throws:
      UnassignedDatasetException - if the class is not set or the instance doesn't have access to a dataset

    • classIndex

      int classIndex()
      Returns the class attribute's index.
      Returns:
      the class index as an integer
      Throws:
      UnassignedDatasetException - if instance doesn't have access to a dataset

    • classIsMissing

      boolean classIsMissing()
      Tests if an instance's class is missing.
      Returns:
      true if the instance's class is missing
      Throws:
      UnassignedClassException - if the class is not set or the instance doesn't have access to a dataset

    • classValue

      double classValue()
      Returns an instance's class value as a floating-point number.
      Returns:
      the corresponding value as a double (If the corresponding attribute is nominal (or a string) then it returns the value's index as a double).
      Throws:
      UnassignedClassException - if the class is not set or the instance doesn't have access to a dataset

    • copy

      Instance copy(double[] values)
      Copies the instance but fills up its values based on the given array of doubles. The copy has access to the same dataset.
      Parameters:
      values - the array with new values
      Returns:
      the new instance

    • dataset

      Instances dataset()
      Returns the dataset this instance has access to. (ie. obtains information about attribute types from) Null if the instance doesn't have access to a dataset.
      Returns:
      the dataset the instance has accesss to

    • deleteAttributeAt

      void deleteAttributeAt(int position)
      Deletes an attribute at the given position (0 to numAttributes() - 1). Only succeeds if the instance does not have access to any dataset because otherwise inconsistencies could be introduced.
      Parameters:
      position - the attribute's position
      Throws:
      RuntimeException - if the instance has access to a dataset

    • enumerateAttributes

      Enumeration<Attribute> enumerateAttributes()
      Returns an enumeration of all the attributes.
      Returns:
      enumeration of all the attributes
      Throws:
      UnassignedDatasetException - if the instance doesn't have access to a dataset

    • equalHeaders

      boolean equalHeaders(Instance inst)
      Tests if the headers of two instances are equivalent.
      Parameters:
      inst - another instance
      Returns:
      true if the header of the given instance is equivalent to this instance's header
      Throws:
      UnassignedDatasetException - if instance doesn't have access to any dataset

    • equalHeadersMsg

      String equalHeadersMsg(Instance inst)
      Checks if the headers of two instances are equivalent. If not, then returns a message why they differ.
      Parameters:
      inst - another instance
      Returns:
      null if the header of the given instance is equivalent to this instance's header, otherwise a message with details on why they differ

    • hasMissingValue

      boolean hasMissingValue()
      Tests whether an instance has a missing value. Skips the class attribute if set.
      Returns:
      true if instance has a missing value.
      Throws:
      UnassignedDatasetException - if instance doesn't have access to any dataset

    • index

      int index(int position)
      Returns the index of the attribute stored at the given position in the sparse representation. Identify function for an instance of type DenseInstance.
      Parameters:
      position - the position
      Returns:
      the index of the attribute stored at the given position

    • insertAttributeAt

      void insertAttributeAt(int position)
      Inserts an attribute at the given position (0 to numAttributes()). Only succeeds if the instance does not have access to any dataset because otherwise inconsistencies could be introduced.
      Parameters:
      position - the attribute's position
      Throws:
      RuntimeException - if the instance has accesss to a dataset
      IllegalArgumentException - if the position is out of range

    • isMissing

      boolean isMissing(int attIndex)
      Tests if a specific value is "missing".
      Parameters:
      attIndex - the attribute's index
      Returns:
      true if the value is "missing"

    • isMissingSparse

      boolean isMissingSparse(int indexOfIndex)
      Tests if a specific value is "missing" in the sparse representation. Samse as isMissing(int) for a DenseInstance.
      Parameters:
      indexOfIndex - the index of the attribute's index
      Returns:
      true if the value is "missing"

    • isMissing

      boolean isMissing(Attribute att)
      Tests if a specific value is "missing". The given attribute has to belong to a dataset.
      Parameters:
      att - the attribute
      Returns:
      true if the value is "missing"

    • mergeInstance

      Instance mergeInstance(Instance inst)
      Merges this instance with the given instance and returns the result. Dataset is set to null. The returned instance is of the same type as this instance.
      Parameters:
      inst - the instance to be merged with this one
      Returns:
      the merged instances

    • numAttributes

      int numAttributes()
      Returns the number of attributes.
      Returns:
      the number of attributes as an integer

    • numClasses

      int numClasses()
      Returns the number of class labels.
      Returns:
      the number of class labels as an integer if the class attribute is nominal, 1 otherwise.
      Throws:
      UnassignedDatasetException - if instance doesn't have access to any dataset

    • numValues

      int numValues()
      Returns the number of values present in a sparse representation.
      Returns:
      the number of values

    • replaceMissingValues

      void replaceMissingValues(double[] array)
      Replaces all missing values in the instance with the values contained in the given array. A deep copy of the vector of attribute values is performed before the values are replaced.
      Parameters:
      array - containing the means and modes
      Throws:
      IllegalArgumentException - if numbers of attributes are unequal

    • setClassMissing

      void setClassMissing()
      Sets the class value of an instance to be "missing". A deep copy of the vector of attribute values is performed before the value is set to be missing.
      Throws:
      UnassignedClassException - if the class is not set
      UnassignedDatasetException - if the instance doesn't have access to a dataset

    • setClassValue

      void setClassValue(double value)
      Sets the class value of an instance to the given value (internal floating-point format). A deep copy of the vector of attribute values is performed before the value is set.
      Parameters:
      value - the new attribute value (If the corresponding attribute is nominal (or a string) then this is the new value's index as a double).
      Throws:
      UnassignedClassException - if the class is not set
      UnassignedDatasetException - if the instance doesn't have access to a dataset

    • setClassValue

      void setClassValue(String value)
      Sets the class value of an instance to the given value. A deep copy of the vector of attribute values is performed before the value is set.
      Parameters:
      value - the new class value (If the class is a string attribute and the value can't be found, the value is added to the attribute).
      Throws:
      UnassignedClassException - if the class is not set
      UnassignedDatasetException - if the dataset is not set
      IllegalArgumentException - if the attribute is not nominal or a string, or the value couldn't be found for a nominal attribute

    • setDataset

      void setDataset(Instances instances)
      Sets the reference to the dataset. Does not check if the instance is compatible with the dataset. Note: the dataset does not know about this instance. If the structure of the dataset's header gets changed, this instance will not be adjusted automatically.
      Parameters:
      instances - the reference to the dataset

    • setMissing

      void setMissing(int attIndex)
      Sets a specific value to be "missing". Performs a deep copy of the vector of attribute values before the value is set to be missing.
      Parameters:
      attIndex - the attribute's index

    • setMissing

      void setMissing(Attribute att)
      Sets a specific value to be "missing". Performs a deep copy of the vector of attribute values before the value is set to be missing. The given attribute has to belong to a dataset.
      Parameters:
      att - the attribute

    • setValue

      void setValue(int attIndex, double value)
      Sets a specific value in the instance to the given value (internal floating-point format). Performs a deep copy of the vector of attribute values before the value is set.
      Parameters:
      attIndex - the attribute's index
      value - the new attribute value (If the corresponding attribute is nominal (or a string) then this is the new value's index as a double).

    • setValueSparse

      void setValueSparse(int indexOfIndex, double value)
      Sets a specific value in the instance to the given value (internal floating-point format), given an index into the sparse representation. Performs a deep copy of the vector of attribute values before the value is set. Same as setValue(int, double) for a DenseInstance.
      Parameters:
      indexOfIndex - the index of the attribute's index
      value - the new attribute value (If the corresponding attribute is nominal (or a string) then this is the new value's index as a double).

    • setValue

      void setValue(int attIndex, String value)
      Sets a value of a nominal or string attribute to the given value. Performs a deep copy of the vector of attribute values before the value is set.
      Parameters:
      attIndex - the attribute's index
      value - the new attribute value (If the attribute is a string attribute and the value can't be found, the value is added to the attribute).
      Throws:
      UnassignedDatasetException - if the dataset is not set
      IllegalArgumentException - if the selected attribute is not nominal or a string, or the supplied value couldn't be found for a nominal attribute

    • setValue

      void setValue(Attribute att, double value)
      Sets a specific value in the instance to the given value (internal floating-point format). Performs a deep copy of the vector of attribute values before the value is set, so if you are planning on calling setValue many times it may be faster to create a new instance using toDoubleArray. The given attribute has to belong to a dataset.
      Parameters:
      att - the attribute
      value - the new attribute value (If the corresponding attribute is nominal (or a string) then this is the new value's index as a double).

    • setValue

      void setValue(Attribute att, String value)
      Sets a value of an nominal or string attribute to the given value. Performs a deep copy of the vector of attribute values before the value is set, so if you are planning on calling setValue many times it may be faster to create a new instance using toDoubleArray. The given attribute has to belong to a dataset.
      Parameters:
      att - the attribute
      value - the new attribute value (If the attribute is a string attribute and the value can't be found, the value is added to the attribute).
      Throws:
      IllegalArgumentException - if the the attribute is not nominal or a string, or the value couldn't be found for a nominal attribute

    • setWeight

      void setWeight(double weight)
      Sets the weight of an instance.
      Parameters:
      weight - the weight

    • relationalValue

      Instances relationalValue(int attIndex)
      Returns the relational value of a relational attribute.
      Parameters:
      attIndex - the attribute's index
      Returns:
      the corresponding relation as an Instances object
      Throws:
      IllegalArgumentException - if the attribute is not a relation-valued attribute
      UnassignedDatasetException - if the instance doesn't belong to a dataset.

    • relationalValue

      Instances relationalValue(Attribute att)
      Returns the relational value of a relational attribute.
      Parameters:
      att - the attribute
      Returns:
      the corresponding relation as an Instances object
      Throws:
      IllegalArgumentException - if the attribute is not a relation-valued attribute
      UnassignedDatasetException - if the instance doesn't belong to a dataset.

    • stringValue

      String stringValue(int attIndex)
      Returns the value of a nominal, string, date, or relational attribute for the instance as a string.
      Parameters:
      attIndex - the attribute's index
      Returns:
      the value as a string
      Throws:
      IllegalArgumentException - if the attribute is not a nominal, string, date, or relation-valued attribute.
      UnassignedDatasetException - if the instance doesn't belong to a dataset.

    • stringValue

      String stringValue(Attribute att)
      Returns the value of a nominal, string, date, or relational attribute for the instance as a string.
      Parameters:
      att - the attribute
      Returns:
      the value as a string
      Throws:
      IllegalArgumentException - if the attribute is not a nominal, string, date, or relation-valued attribute.
      UnassignedDatasetException - if the instance doesn't belong to a dataset.

    • toDoubleArray

      double[] toDoubleArray()
      Returns the values of each attribute as an array of doubles. Creates a fresh array object for this.
      Returns:
      an array containing all the instance attribute values

    • toStringNoWeight

      String toStringNoWeight(int afterDecimalPoint)
      Returns the description of one instance (without weight appended). If the instance doesn't have access to a dataset, it returns the internal floating-point values. Quotes string values that contain whitespace characters. This method is used by getRandomNumberGenerator() in Instances.java in order to maintain backwards compatibility with weka 3.4.
      Parameters:
      afterDecimalPoint - maximum number of digits after the decimal point for numeric values
      Returns:
      the instance's description as a string

    • toStringNoWeight

      String toStringNoWeight()
      Returns the description of one instance (without weight appended). If the instance doesn't have access to a dataset, it returns the internal floating-point values. Quotes string values that contain whitespace characters. This method is used by getRandomNumberGenerator() in Instances.java in order to maintain backwards compatibility with weka 3.4.
      Returns:
      the instance's description as a string

    • toStringMaxDecimalDigits

      String toStringMaxDecimalDigits(int afterDecimalPoint)
      Returns the description of one instance with any numeric values printed at the supplied maximum number of decimal places. If the instance doesn't have access to a dataset, it returns the internal floating-point values. Quotes string values that contain whitespace characters.
      Parameters:
      afterDecimalPoint - the maximum number of digits permitted after the decimal point for a numeric value
      Returns:
      the instance's description as a string

    • toString

      String toString(int attIndex, int afterDecimalPoint)
      Returns the description of one value of the instance as a string. If the instance doesn't have access to a dataset, it returns the internal floating-point value. Quotes string values that contain whitespace characters, or if they are a question mark.
      Parameters:
      attIndex - the attribute's index
      afterDecimalPoint - the maximum number of digits permitted after the decimal point for numeric values
      Returns:
      the value's description as a string

    • toString

      String toString(int attIndex)
      Returns the description of one value of the instance as a string. If the instance doesn't have access to a dataset, it returns the internal floating-point value. Quotes string values that contain whitespace characters, or if they are a question mark.
      Parameters:
      attIndex - the attribute's index
      Returns:
      the value's description as a string

    • toString

      String toString(Attribute att, int afterDecimalPoint)
      Returns the description of one value of the instance as a string. If the instance doesn't have access to a dataset it returns the internal floating-point value. Quotes string values that contain whitespace characters, or if they are a question mark. The given attribute has to belong to a dataset.
      Parameters:
      att - the attribute
      afterDecimalPoint - the maximum number of decimal places to print
      Returns:
      the value's description as a string

    • toString

      String toString(Attribute att)
      Returns the description of one value of the instance as a string. If the instance doesn't have access to a dataset it returns the internal floating-point value. Quotes string values that contain whitespace characters, or if they are a question mark. The given attribute has to belong to a dataset.
      Parameters:
      att - the attribute
      Returns:
      the value's description as a string

    • value

      double value(int attIndex)
      Returns an instance's attribute value in internal format.
      Parameters:
      attIndex - the attribute's index
      Returns:
      the specified value as a double (If the corresponding attribute is nominal (or a string) then it returns the value's index as a double).

    • valueSparse

      double valueSparse(int indexOfIndex)
      Returns an instance's attribute value in internal format, given an index in the sparse representation. Same as value(int) for a DenseInstance.
      Parameters:
      indexOfIndex - the index of the attribute's index
      Returns:
      the specified value as a double (If the corresponding attribute is nominal (or a string) then it returns the value's index as a double).

    • value

      double value(Attribute att)
      Returns an instance's attribute value in internal format. The given attribute has to belong to a dataset.
      Parameters:
      att - the attribute
      Returns:
      the specified value as a double (If the corresponding attribute is nominal (or a string) then it returns the value's index as a double).

    • weight

      double weight()
      Returns the instance's weight.
      Returns:
      the instance's weight as a double