Package weka.core
Class Attribute
- java.lang.Object
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- weka.core.Attribute
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- All Implemented Interfaces:
java.io.Serializable
,Copyable
,RevisionHandler
public class Attribute extends java.lang.Object implements Copyable, java.io.Serializable, RevisionHandler
Class for handling an attribute. Once an attribute has been created, it can't be changed.The following attribute types are supported:
- numeric:
This type of attribute represents a floating-point number. - nominal:
This type of attribute represents a fixed set of nominal values. - string:
This type of attribute represents a dynamically expanding set of nominal values. Usually used in text classification. - date:
This type of attribute represents a date, internally represented as floating-point number storing the milliseconds since January 1, 1970, 00:00:00 GMT. The string representation of the date must be ISO-8601 compliant, the default isyyyy-MM-dd'T'HH:mm:ss
. - relational:
This type of attribute can contain other attributes and is, e.g., used for representing Multi-Instance data. (Multi-Instance data consists of a nominal attribute containing the bag-id, then a relational attribute with all the attributes of the bag, and finally the class attribute.)
...
// Create numeric attributes "length" and "weight"
Attribute length = new Attribute("length");
Attribute weight = new Attribute("weight");
// Create vector to hold nominal values "first", "second", "third"
FastVector my_nominal_values = new FastVector(3);
my_nominal_values.addElement("first");
my_nominal_values.addElement("second");
my_nominal_values.addElement("third");
// Create nominal attribute "position"
Attribute position = new Attribute("position", my_nominal_values);
...
- Version:
- $Revision: 9518 $
- Author:
- Eibe Frank (eibe@cs.waikato.ac.nz)
- See Also:
- Serialized Form
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Field Summary
Fields Modifier and Type Field Description static java.lang.String
ARFF_ATTRIBUTE
The keyword used to denote the start of an arff attribute declarationstatic java.lang.String
ARFF_ATTRIBUTE_DATE
The keyword used to denote a date attributestatic java.lang.String
ARFF_ATTRIBUTE_INTEGER
A keyword used to denote a numeric attributestatic java.lang.String
ARFF_ATTRIBUTE_NUMERIC
A keyword used to denote a numeric attributestatic java.lang.String
ARFF_ATTRIBUTE_REAL
A keyword used to denote a numeric attributestatic java.lang.String
ARFF_ATTRIBUTE_RELATIONAL
The keyword used to denote a relation-valued attributestatic java.lang.String
ARFF_ATTRIBUTE_STRING
The keyword used to denote a string attributestatic java.lang.String
ARFF_END_SUBRELATION
The keyword used to denote the end of the declaration of a subrelationstatic int
DATE
Constant set for attributes with date values.static java.lang.String
DUMMY_STRING_VAL
Dummy first value for String attributes (useful for sparse instances)static int
NOMINAL
Constant set for nominal attributes.static int
NUMERIC
Constant set for numeric attributes.static int
ORDERING_MODULO
Constant set for modulo-ordered attributes.static int
ORDERING_ORDERED
Constant set for ordered attributes.static int
ORDERING_SYMBOLIC
Constant set for symbolic attributes.static int
RELATIONAL
Constant set for relation-valued attributes.static int
STRING
Constant set for attributes with string values.
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Constructor Summary
Constructors Constructor Description Attribute(java.lang.String attributeName)
Constructor for a numeric attribute.Attribute(java.lang.String attributeName, int index)
Constructor for a numeric attribute with a particular index.Attribute(java.lang.String attributeName, java.lang.String dateFormat)
Constructor for a date attribute.Attribute(java.lang.String attributeName, java.lang.String dateFormat, int index)
Constructor for date attributes with a particular index.Attribute(java.lang.String attributeName, java.lang.String dateFormat, ProtectedProperties metadata)
Constructor for a date attribute, where metadata is supplied.Attribute(java.lang.String attributeName, FastVector attributeValues)
Constructor for nominal attributes and string attributes.Attribute(java.lang.String attributeName, FastVector attributeValues, int index)
Constructor for nominal attributes and string attributes with a particular index.Attribute(java.lang.String attributeName, FastVector attributeValues, ProtectedProperties metadata)
Constructor for nominal attributes and string attributes, where metadata is supplied.Attribute(java.lang.String attributeName, Instances header)
Constructor for relation-valued attributes.Attribute(java.lang.String attributeName, Instances header, int index)
Constructor for a relation-valued attribute with a particular index.Attribute(java.lang.String attributeName, Instances header, ProtectedProperties metadata)
Constructor for relation-valued attributes.Attribute(java.lang.String attributeName, ProtectedProperties metadata)
Constructor for a numeric attribute, where metadata is supplied.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description int
addRelation(Instances value)
Adds a relation to a relation-valued attribute.int
addStringValue(java.lang.String value)
Adds a string value to the list of valid strings for attributes of type STRING and returns the index of the string.int
addStringValue(Attribute src, int index)
Adds a string value to the list of valid strings for attributes of type STRING and returns the index of the string.java.lang.Object
copy()
Produces a shallow copy of this attribute.Attribute
copy(java.lang.String newName)
Produces a shallow copy of this attribute with a new name.java.util.Enumeration
enumerateValues()
Returns an enumeration of all the attribute's values if the attribute is nominal, string, or relation-valued, null otherwise.boolean
equals(java.lang.Object other)
Tests if given attribute is equal to this attribute.java.lang.String
formatDate(double date)
Returns the given amount of milliseconds formatted according to the current Date format.java.lang.String
getDateFormat()
Returns the Date format pattern in case this attribute is of type DATE, otherwise an empty string.double
getLowerNumericBound()
Returns the lower bound of a numeric attribute.ProtectedProperties
getMetadata()
Returns the properties supplied for this attribute.java.lang.String
getRevision()
Returns the revision string.double
getUpperNumericBound()
Returns the upper bound of a numeric attribute.boolean
hasZeropoint()
Returns whether the attribute has a zeropoint and may be added meaningfully.int
index()
Returns the index of this attribute.int
indexOfValue(java.lang.String value)
Returns the index of a given attribute value.boolean
isAveragable()
Returns whether the attribute can be averaged meaningfully.boolean
isDate()
Tests if the attribute is a date type.boolean
isInRange(double value)
Determines whether a value lies within the bounds of the attribute.boolean
isNominal()
Test if the attribute is nominal.boolean
isNumeric()
Tests if the attribute is numeric.boolean
isRegular()
Returns whether the attribute values are equally spaced.boolean
isRelationValued()
Tests if the attribute is relation valued.boolean
isString()
Tests if the attribute is a string.boolean
lowerNumericBoundIsOpen()
Returns whether the lower numeric bound of the attribute is open.static void
main(java.lang.String[] ops)
Simple main method for testing this class.java.lang.String
name()
Returns the attribute's name.int
numValues()
Returns the number of attribute values.int
ordering()
Returns the ordering of the attribute.double
parseDate(java.lang.String string)
Parses the given String as Date, according to the current format and returns the corresponding amount of milliseconds.Instances
relation()
Returns the header info for a relation-valued attribute, null if the attribute is not relation-valued.Instances
relation(int valIndex)
Returns a value of a relation-valued attribute.void
setWeight(double value)
Sets the new attribute's weightjava.lang.String
toString()
Returns a description of this attribute in ARFF format.int
type()
Returns the attribute's type as an integer.boolean
upperNumericBoundIsOpen()
Returns whether the upper numeric bound of the attribute is open.java.lang.String
value(int valIndex)
Returns a value of a nominal or string attribute.double
weight()
Returns the attribute's weight.
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Field Detail
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NUMERIC
public static final int NUMERIC
Constant set for numeric attributes.- See Also:
- Constant Field Values
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NOMINAL
public static final int NOMINAL
Constant set for nominal attributes.- See Also:
- Constant Field Values
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STRING
public static final int STRING
Constant set for attributes with string values.- See Also:
- Constant Field Values
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DATE
public static final int DATE
Constant set for attributes with date values.- See Also:
- Constant Field Values
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RELATIONAL
public static final int RELATIONAL
Constant set for relation-valued attributes.- See Also:
- Constant Field Values
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ORDERING_SYMBOLIC
public static final int ORDERING_SYMBOLIC
Constant set for symbolic attributes.- See Also:
- Constant Field Values
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ORDERING_ORDERED
public static final int ORDERING_ORDERED
Constant set for ordered attributes.- See Also:
- Constant Field Values
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ORDERING_MODULO
public static final int ORDERING_MODULO
Constant set for modulo-ordered attributes.- See Also:
- Constant Field Values
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ARFF_ATTRIBUTE
public static final java.lang.String ARFF_ATTRIBUTE
The keyword used to denote the start of an arff attribute declaration- See Also:
- Constant Field Values
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ARFF_ATTRIBUTE_INTEGER
public static final java.lang.String ARFF_ATTRIBUTE_INTEGER
A keyword used to denote a numeric attribute- See Also:
- Constant Field Values
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ARFF_ATTRIBUTE_REAL
public static final java.lang.String ARFF_ATTRIBUTE_REAL
A keyword used to denote a numeric attribute- See Also:
- Constant Field Values
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ARFF_ATTRIBUTE_NUMERIC
public static final java.lang.String ARFF_ATTRIBUTE_NUMERIC
A keyword used to denote a numeric attribute- See Also:
- Constant Field Values
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ARFF_ATTRIBUTE_STRING
public static final java.lang.String ARFF_ATTRIBUTE_STRING
The keyword used to denote a string attribute- See Also:
- Constant Field Values
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ARFF_ATTRIBUTE_DATE
public static final java.lang.String ARFF_ATTRIBUTE_DATE
The keyword used to denote a date attribute- See Also:
- Constant Field Values
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ARFF_ATTRIBUTE_RELATIONAL
public static final java.lang.String ARFF_ATTRIBUTE_RELATIONAL
The keyword used to denote a relation-valued attribute- See Also:
- Constant Field Values
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ARFF_END_SUBRELATION
public static final java.lang.String ARFF_END_SUBRELATION
The keyword used to denote the end of the declaration of a subrelation- See Also:
- Constant Field Values
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DUMMY_STRING_VAL
public static final java.lang.String DUMMY_STRING_VAL
Dummy first value for String attributes (useful for sparse instances)- See Also:
- Constant Field Values
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Constructor Detail
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Attribute
public Attribute(java.lang.String attributeName)
Constructor for a numeric attribute.- Parameters:
attributeName
- the name for the attribute
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Attribute
public Attribute(java.lang.String attributeName, ProtectedProperties metadata)
Constructor for a numeric attribute, where metadata is supplied.- Parameters:
attributeName
- the name for the attributemetadata
- the attribute's properties
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Attribute
public Attribute(java.lang.String attributeName, java.lang.String dateFormat)
Constructor for a date attribute.- Parameters:
attributeName
- the name for the attributedateFormat
- a string suitable for use with SimpleDateFormatter for parsing dates.
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Attribute
public Attribute(java.lang.String attributeName, java.lang.String dateFormat, ProtectedProperties metadata)
Constructor for a date attribute, where metadata is supplied.- Parameters:
attributeName
- the name for the attributedateFormat
- a string suitable for use with SimpleDateFormatter for parsing dates.metadata
- the attribute's properties
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Attribute
public Attribute(java.lang.String attributeName, FastVector attributeValues)
Constructor for nominal attributes and string attributes. If a null vector of attribute values is passed to the method, the attribute is assumed to be a string.- Parameters:
attributeName
- the name for the attributeattributeValues
- a vector of strings denoting the attribute values. Null if the attribute is a string attribute.
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Attribute
public Attribute(java.lang.String attributeName, FastVector attributeValues, ProtectedProperties metadata)
Constructor for nominal attributes and string attributes, where metadata is supplied. If a null vector of attribute values is passed to the method, the attribute is assumed to be a string.- Parameters:
attributeName
- the name for the attributeattributeValues
- a vector of strings denoting the attribute values. Null if the attribute is a string attribute.metadata
- the attribute's properties
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Attribute
public Attribute(java.lang.String attributeName, Instances header)
Constructor for relation-valued attributes.- Parameters:
attributeName
- the name for the attributeheader
- an Instances object specifying the header of the relation.
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Attribute
public Attribute(java.lang.String attributeName, Instances header, ProtectedProperties metadata)
Constructor for relation-valued attributes.- Parameters:
attributeName
- the name for the attributeheader
- an Instances object specifying the header of the relation.metadata
- the attribute's properties
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Attribute
public Attribute(java.lang.String attributeName, int index)
Constructor for a numeric attribute with a particular index.- Parameters:
attributeName
- the name for the attributeindex
- the attribute's index
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Attribute
public Attribute(java.lang.String attributeName, java.lang.String dateFormat, int index)
Constructor for date attributes with a particular index.- Parameters:
attributeName
- the name for the attributedateFormat
- a string suitable for use with SimpleDateFormatter for parsing dates. Null for a default format string.index
- the attribute's index
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Attribute
public Attribute(java.lang.String attributeName, FastVector attributeValues, int index)
Constructor for nominal attributes and string attributes with a particular index. If a null vector of attribute values is passed to the method, the attribute is assumed to be a string.- Parameters:
attributeName
- the name for the attributeattributeValues
- a vector of strings denoting the attribute values. Null if the attribute is a string attribute.index
- the attribute's index
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Attribute
public Attribute(java.lang.String attributeName, Instances header, int index)
Constructor for a relation-valued attribute with a particular index.- Parameters:
attributeName
- the name for the attributeheader
- the header information for this attributeindex
- the attribute's index
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Method Detail
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copy
public java.lang.Object copy()
Produces a shallow copy of this attribute.
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enumerateValues
public final java.util.Enumeration enumerateValues()
Returns an enumeration of all the attribute's values if the attribute is nominal, string, or relation-valued, null otherwise.- Returns:
- enumeration of all the attribute's values
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equals
public final boolean equals(java.lang.Object other)
Tests if given attribute is equal to this attribute.- Overrides:
equals
in classjava.lang.Object
- Parameters:
other
- the Object to be compared to this attribute- Returns:
- true if the given attribute is equal to this attribute
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index
public final int index()
Returns the index of this attribute.- Returns:
- the index of this attribute
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indexOfValue
public final int indexOfValue(java.lang.String value)
Returns the index of a given attribute value. (The index of the first occurence of this value.)- Parameters:
value
- the value for which the index is to be returned- Returns:
- the index of the given attribute value if attribute is nominal or a string, -1 if it is not or the value can't be found
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isNominal
public final boolean isNominal()
Test if the attribute is nominal.- Returns:
- true if the attribute is nominal
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isNumeric
public final boolean isNumeric()
Tests if the attribute is numeric.- Returns:
- true if the attribute is numeric
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isRelationValued
public final boolean isRelationValued()
Tests if the attribute is relation valued.- Returns:
- true if the attribute is relation valued
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isString
public final boolean isString()
Tests if the attribute is a string.- Returns:
- true if the attribute is a string
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isDate
public final boolean isDate()
Tests if the attribute is a date type.- Returns:
- true if the attribute is a date type
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name
public final java.lang.String name()
Returns the attribute's name.- Returns:
- the attribute's name as a string
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numValues
public final int numValues()
Returns the number of attribute values. Returns 0 for attributes that are not either nominal, string, or relation-valued.- Returns:
- the number of attribute values
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toString
public final java.lang.String toString()
Returns a description of this attribute in ARFF format. Quotes strings if they contain whitespace characters, or if they are a question mark.- Overrides:
toString
in classjava.lang.Object
- Returns:
- a description of this attribute as a string
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type
public final int type()
Returns the attribute's type as an integer.- Returns:
- the attribute's type.
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getDateFormat
public final java.lang.String getDateFormat()
Returns the Date format pattern in case this attribute is of type DATE, otherwise an empty string.- Returns:
- the date format pattern
- See Also:
SimpleDateFormat
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value
public final java.lang.String value(int valIndex)
Returns a value of a nominal or string attribute. Returns an empty string if the attribute is neither a string nor a nominal attribute.- Parameters:
valIndex
- the value's index- Returns:
- the attribute's value as a string
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relation
public final Instances relation()
Returns the header info for a relation-valued attribute, null if the attribute is not relation-valued.- Returns:
- the attribute's value as an Instances object
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relation
public final Instances relation(int valIndex)
Returns a value of a relation-valued attribute. Returns null if the attribute is not relation-valued.- Parameters:
valIndex
- the value's index- Returns:
- the attribute's value as an Instances object
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addStringValue
public int addStringValue(java.lang.String value)
Adds a string value to the list of valid strings for attributes of type STRING and returns the index of the string.- Parameters:
value
- The string value to add- Returns:
- the index assigned to the string, or -1 if the attribute is not of type Attribute.STRING
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addStringValue
public int addStringValue(Attribute src, int index)
Adds a string value to the list of valid strings for attributes of type STRING and returns the index of the string. This method is more efficient than addStringValue(String) for long strings.- Parameters:
src
- The Attribute containing the string value to add.index
- the index of the string value in the source attribute.- Returns:
- the index assigned to the string, or -1 if the attribute is not of type Attribute.STRING
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addRelation
public int addRelation(Instances value)
Adds a relation to a relation-valued attribute.- Parameters:
value
- The value to add- Returns:
- the index assigned to the value, or -1 if the attribute is not of type Attribute.RELATIONAL
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copy
public final Attribute copy(java.lang.String newName)
Produces a shallow copy of this attribute with a new name.- Parameters:
newName
- the name of the new attribute- Returns:
- a copy of this attribute with the same index
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formatDate
public java.lang.String formatDate(double date)
Returns the given amount of milliseconds formatted according to the current Date format.- Parameters:
date
- the date, represented in milliseconds since January 1, 1970, 00:00:00 GMT, to return as string- Returns:
- the formatted date
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parseDate
public double parseDate(java.lang.String string) throws java.text.ParseException
Parses the given String as Date, according to the current format and returns the corresponding amount of milliseconds.- Parameters:
string
- the date to parse- Returns:
- the date in milliseconds since January 1, 1970, 00:00:00 GMT
- Throws:
java.text.ParseException
- if parsing fails
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getMetadata
public final ProtectedProperties getMetadata()
Returns the properties supplied for this attribute.- Returns:
- metadata for this attribute
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ordering
public final int ordering()
Returns the ordering of the attribute. One of the following: ORDERING_SYMBOLIC - attribute values should be treated as symbols. ORDERING_ORDERED - attribute values have a global ordering. ORDERING_MODULO - attribute values have an ordering which wraps.- Returns:
- the ordering type of the attribute
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isRegular
public final boolean isRegular()
Returns whether the attribute values are equally spaced.- Returns:
- whether the attribute is regular or not
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isAveragable
public final boolean isAveragable()
Returns whether the attribute can be averaged meaningfully.- Returns:
- whether the attribute can be averaged or not
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hasZeropoint
public final boolean hasZeropoint()
Returns whether the attribute has a zeropoint and may be added meaningfully.- Returns:
- whether the attribute has a zeropoint or not
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weight
public final double weight()
Returns the attribute's weight.- Returns:
- the attribute's weight as a double
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setWeight
public void setWeight(double value)
Sets the new attribute's weight- Parameters:
value
- the new weight
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getLowerNumericBound
public final double getLowerNumericBound()
Returns the lower bound of a numeric attribute.- Returns:
- the lower bound of the specified numeric range
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lowerNumericBoundIsOpen
public final boolean lowerNumericBoundIsOpen()
Returns whether the lower numeric bound of the attribute is open.- Returns:
- whether the lower numeric bound is open or not (closed)
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getUpperNumericBound
public final double getUpperNumericBound()
Returns the upper bound of a numeric attribute.- Returns:
- the upper bound of the specified numeric range
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upperNumericBoundIsOpen
public final boolean upperNumericBoundIsOpen()
Returns whether the upper numeric bound of the attribute is open.- Returns:
- whether the upper numeric bound is open or not (closed)
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isInRange
public final boolean isInRange(double value)
Determines whether a value lies within the bounds of the attribute.- Parameters:
value
- the value to check- Returns:
- whether the value is in range
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getRevision
public java.lang.String getRevision()
Returns the revision string.- Specified by:
getRevision
in interfaceRevisionHandler
- Returns:
- the revision
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main
public static void main(java.lang.String[] ops)
Simple main method for testing this class.- Parameters:
ops
- the commandline options
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