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Class weka.core.SparseInstance

java.lang.Object
    |
    +----weka.core.Instance
            |
            +----weka.core.SparseInstance

public class SparseInstance
extends Instance
Class for storing an instance as a sparse vector. A sparse instance only requires storage for those attribute values that are non-zero. Since the objective is to reduce storage requirements for datasets with large numbers of default values, this also includes nominal attributes -- the first nominal value (i.e. that which has index 0) will not require explicit storage, so rearrange your nominal attribute value orderings if necessary. Missing values will be stored explicitly.


Constructor Index

 o SparseInstance(double, double[])
Constructor that generates a sparse instance from the given parameters.
 o SparseInstance(double, double[], int[], int)
Constructor that inititalizes instance variable with given values.
 o SparseInstance(Instance)
Constructor that generates a sparse instance from the given instance.
 o SparseInstance(int)
Constructor of an instance that sets weight to one, all values to be missing, and the reference to the dataset to null.
 o SparseInstance(SparseInstance)
Constructor that copies the info from the given instance.

Method Index

 o attributeSparse(int)
Returns the attribute associated with the internal index.
 o copy()
Produces a shallow copy of this instance.
 o index(int)
Returns the index of the attribute stored at the given position.
 o isMissing(int)
Tests if a specific value is "missing".
 o locateIndex(int)
Locates the greatest index that is not greater than the given index.
 o main(String[])
Main method for testing this class.
 o mergeInstance(Instance)
Merges this instance with the given instance and returns the result.
 o numAttributes()
Returns the number of attributes.
 o numValues()
Returns the number of values in the sparse vector.
 o replaceMissingValues(double[])
Replaces all missing values in the instance with the values contained in the given array.
 o setValue(int, double)
Sets a specific value in the instance to the given value (internal floating-point format).
 o setValueSparse(int, double)
Sets a specific value in the instance to the given value (internal floating-point format).
 o toDoubleArray()
Returns the values of each attribute as an array of doubles.
 o toString()
Returns the description of one instance in sparse format.
 o value(int)
Returns an instance's attribute value in internal format.

Constructor Detail

 o SparseInstance
public SparseInstance(Instance instance)
          Constructor that generates a sparse instance from the given instance. Reference to the dataset is set to null. (ie. the instance doesn't have access to information about the attribute types)
Parameters:
instance - the instance from which the attribute values and the weight are to be copied
 o SparseInstance
public SparseInstance(SparseInstance instance)
          Constructor that copies the info from the given instance. Reference to the dataset is set to null. (ie. the instance doesn't have access to information about the attribute types)
Parameters:
instance - the instance from which the attribute info is to be copied
 o SparseInstance
public SparseInstance(double weight,
                      double attValues[])
          Constructor that generates a sparse instance from the given parameters. Reference to the dataset is set to null. (ie. the instance doesn't have access to information about the attribute types)
Parameters:
weight - the instance's weight
attValues - a vector of attribute values
 o SparseInstance
public SparseInstance(double weight,
                      double attValues[],
                      int indices[],
                      int maxNumValues)
          Constructor that inititalizes instance variable with given values. Reference to the dataset is set to null. (ie. the instance doesn't have access to information about the attribute types)
Parameters:
weight - the instance's weight
attValues - a vector of attribute values (just the ones to be stored)
indices - the indices of the given values in the full vector
maxNumValues - the maximium number of values that can be stored
 o SparseInstance
public SparseInstance(int numAttributes)
          Constructor of an instance that sets weight to one, all values to be missing, and the reference to the dataset to null. (ie. the instance doesn't have access to information about the attribute types)
Parameters:
numAttributes - the size of the instance

Method Detail

 o attributeSparse
public Attribute attributeSparse(int indexOfIndex)
          Returns the attribute associated with the internal index.
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
Overrides:
attributeSparse in class Instance
 o copy
public java.lang.Object copy()
          Produces a shallow copy of this instance. The copy has access to the same dataset. (if you want to make a copy that doesn't have access to the dataset, use new SparseInstance(instance)
Returns:
the shallow copy
Overrides:
copy in class Instance
 o index
public int index(int position)
          Returns the index of the attribute stored at the given position.
Parameters:
position - the position
Returns:
the index of the attribute stored at the given position
Overrides:
index in class Instance
 o isMissing
public boolean isMissing(int attIndex)
          Tests if a specific value is "missing".
Parameters:
attIndex - the attribute's index
Overrides:
isMissing in class Instance
 o locateIndex
public int locateIndex(int index)
          Locates the greatest index that is not greater than the given index.
Returns:
the internal index of the attribute index. Returns -1 if no index with this property couldn't be found
 o mergeInstance
public Instance mergeInstance(Instance inst)
          Merges this instance with the given instance and returns the result. Dataset is set to null.
Parameters:
inst - the instance to be merged with this one
Returns:
the merged instances
Overrides:
mergeInstance in class Instance
 o numAttributes
public int numAttributes()
          Returns the number of attributes.
Returns:
the number of attributes as an integer
Overrides:
numAttributes in class Instance
 o numValues
public int numValues()
          Returns the number of values in the sparse vector.
Returns:
the number of values
Overrides:
numValues in class Instance
 o replaceMissingValues
public 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:
java.lang.IllegalArgumentException - if numbers of attributes are unequal
Overrides:
replaceMissingValues in class Instance
 o setValue
public 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).
Overrides:
setValue in class Instance
 o setValueSparse
public void setValueSparse(int indexOfIndex,
                           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:
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).
Overrides:
setValueSparse in class Instance
 o toDoubleArray
public double[] toDoubleArray()
          Returns the values of each attribute as an array of doubles.
Returns:
an array containing all the instance attribute values
Overrides:
toDoubleArray in class Instance
 o toString
public java.lang.String toString()
          Returns the description of one instance in sparse format. If the instance doesn't have access to a dataset, it returns the internal floating-point values. Quotes string values that contain whitespace characters.
Returns:
the instance's description as a string
Overrides:
toString in class Instance
 o value
public 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).
Overrides:
value in class Instance
 o main
public static void main(java.lang.String options[])
          Main method for testing this class.

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