Class Instance
- java.lang.Object
-
- weka.core.Instance
-
- All Implemented Interfaces:
java.io.Serializable
,Copyable
,RevisionHandler
- Direct Known Subclasses:
IndividualInstance
,SparseInstance
public class Instance extends java.lang.Object implements Copyable, java.io.Serializable, RevisionHandler
Class for handling an instance. All values (numeric, date, nominal, string or relational) are internally stored as floating-point numbers. 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 Instance(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 are safe, ie. a change of an instance does not affect any other instances. All methods that change an instance's attribute values clone the attribute value vector before it is changed. If your application heavily modifies instance values, it may be faster to create a new instance from scratch.
- Version:
- $Revision: 9140 $
- Author:
- Eibe Frank (eibe@cs.waikato.ac.nz)
- See Also:
- Serialized Form
-
-
Constructor Summary
Constructors Constructor Description Instance(double weight, double[] attValues)
Constructor that inititalizes instance variable with given values.Instance(int numAttributes)
Constructor of an instance that sets weight to one, all values to be missing, and the reference to the dataset to null.Instance(Instance instance)
Constructor that copies the attribute values and the weight from the given instance.
-
Method Summary
All Methods Static Methods Instance Methods Concrete Methods 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.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 in internal format.java.lang.Object
copy()
Produces a shallow copy of this instance.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).java.util.Enumeration
enumerateAttributes()
Returns an enumeration of all the attributes.boolean
equalHeaders(Instance inst)
Tests if the headers of two instances are equivalent.java.lang.String
getRevision()
Returns the revision string.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.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".static boolean
isMissingValue(double val)
Tests if the given value codes "missing".static void
main(java.lang.String[] options)
Main method for testing this class.Instance
mergeInstance(Instance inst)
Merges this instance with the given instance and returns the result.static double
missingValue()
Returns the double that codes "missing".int
numAttributes()
Returns the number of attributes.int
numClasses()
Returns the number of class labels.int
numValues()
Returns the number of values present.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(java.lang.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, java.lang.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, java.lang.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).void
setWeight(double weight)
Sets the weight of an instance.java.lang.String
stringValue(int attIndex)
Returns the value of a nominal, string, date, or relational attribute for the instance as a string.java.lang.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.java.lang.String
toString()
Returns the description of one instance.java.lang.String
toString(int attIndex)
Returns the description of one value of the instance as a string.java.lang.String
toString(Attribute att)
Returns the description of one value of the instance as a string.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.double
weight()
Returns the instance's weight.
-
-
-
Constructor Detail
-
Instance
public Instance(Instance instance)
Constructor that copies the attribute values and the weight 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
-
Instance
public Instance(double weight, double[] attValues)
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 weightattValues
- a vector of attribute values
-
Instance
public Instance(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
-
attribute
public 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
public Attribute attributeSparse(int indexOfIndex)
Returns the attribute with the given index. Does the same thing as attribute().- 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
public 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
public 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
public 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
public double classValue()
Returns an instance's class value in internal format. (ie. 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
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, usenew Instance(instance)
-
dataset
public 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
public 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:
java.lang.RuntimeException
- if the instance has access to a dataset
-
enumerateAttributes
public java.util.Enumeration 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
public 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
-
hasMissingValue
public 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
public int index(int position)
Returns the index of the attribute stored at the given position. Just returns the given value.- Parameters:
position
- the position- Returns:
- the index of the attribute stored at the given position
-
insertAttributeAt
public 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:
java.lang.RuntimeException
- if the instance has accesss to a datasetjava.lang.IllegalArgumentException
- if the position is out of range
-
isMissing
public 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
public boolean isMissingSparse(int indexOfIndex)
Tests if a specific value is "missing". Does the same thing as isMissing() if applied to an Instance.- Parameters:
indexOfIndex
- the index of the attribute's index- Returns:
- true if the value is "missing"
-
isMissing
public 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"
-
isMissingValue
public static boolean isMissingValue(double val)
Tests if the given value codes "missing".- Parameters:
val
- the value to be tested- Returns:
- true if val codes "missing"
-
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
-
missingValue
public static double missingValue()
Returns the double that codes "missing".- Returns:
- the double that codes "missing"
-
numAttributes
public int numAttributes()
Returns the number of attributes.- Returns:
- the number of attributes as an integer
-
numClasses
public 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
public int numValues()
Returns the number of values present. Always the same as numAttributes().- Returns:
- the number of values
-
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
-
setClassMissing
public 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 setUnassignedDatasetException
- if the instance doesn't have access to a dataset
-
setClassValue
public 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 setUnaddignedDatasetException
- if the instance doesn't have access to a dataset
-
setClassValue
public final void setClassValue(java.lang.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 setUnassignedDatasetException
- if the dataset is not setjava.lang.IllegalArgumentException
- if the attribute is not nominal or a string, or the value couldn't be found for a nominal attribute
-
setDataset
public final 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
public final 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
public final 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
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 indexvalue
- 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
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. Does exactly the same thing as setValue().- Parameters:
indexOfIndex
- the index of the attribute's indexvalue
- 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
public final void setValue(int attIndex, java.lang.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 indexvalue
- 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 setjava.lang.IllegalArgumentException
- if the selected attribute is not nominal or a string, or the supplied value couldn't be found for a nominal attribute
-
setValue
public final 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 attributevalue
- 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
public final void setValue(Attribute att, java.lang.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 attributevalue
- 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:
java.lang.IllegalArgumentException
- if the the attribute is not nominal or a string, or the value couldn't be found for a nominal attribute
-
setWeight
public final void setWeight(double weight)
Sets the weight of an instance.- Parameters:
weight
- the weight
-
relationalValue
public final 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:
java.lang.IllegalArgumentException
- if the attribute is not a relation-valued attributeUnassignedDatasetException
- if the instance doesn't belong to a dataset.
-
relationalValue
public final 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:
java.lang.IllegalArgumentException
- if the attribute is not a relation-valued attributeUnassignedDatasetException
- if the instance doesn't belong to a dataset.
-
stringValue
public final java.lang.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:
java.lang.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
public final java.lang.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:
java.lang.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
public double[] toDoubleArray()
Returns the values of each attribute as an array of doubles.- Returns:
- an array containing all the instance attribute values
-
toString
public java.lang.String toString()
Returns the description of one instance. If the instance doesn't have access to a dataset, it returns the internal floating-point values. Quotes string values that contain whitespace characters.- Overrides:
toString
in classjava.lang.Object
- Returns:
- the instance's description as a string
-
toString
public final java.lang.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
public final java.lang.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
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).
-
valueSparse
public double valueSparse(int indexOfIndex)
Returns an instance's attribute value in internal format. Does exactly the same thing as value() if applied to an Instance.- 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
public 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
public final double weight()
Returns the instance's weight.- Returns:
- the instance's weight as a double
-
main
public static void main(java.lang.String[] options)
Main method for testing this class.- Parameters:
options
- the commandline options - ignored
-
getRevision
public java.lang.String getRevision()
Returns the revision string.- Specified by:
getRevision
in interfaceRevisionHandler
- Returns:
- the revision
-
-