org.grouplens.lenskit.data.pref

Class PreferenceDomain

java.lang.Object

org.grouplens.lenskit.data.pref.PreferenceDomain

All Implemented Interfaces:

Serializable

@Shareable
 @DefaultNull
public final class PreferenceDomain
extends Object
implements Serializable

An object describing the domain of preference data, used in ratings and predictions.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static long	serialVersionUID

Constructor Summary

Constructors

Constructor and Description
PreferenceDomain(double min, double max) Create a continuous bounded preference domain.
PreferenceDomain(double min, double max, double prec) Create a discrete bounded preference domain.

Method Summary

Modifier and Type	Method and Description
double	clampValue(double v) Clamp a value to this preference domain.
void	clampVector(MutableSparseVector vec)
boolean	equals(Object o)
static PreferenceDomain	fromString(String spec) Parse a preference domain from a string specification.
double	getMaximum() The maximum preference value.
double	getMinimum() The minimum preference value.
double	getPrecision() The precision of preference values.
int	hashCode()
boolean	hasPrecision() Query whether this preference domain has a precision.
static PreferenceDomainBuilder	newBuilder() Create a new preference domain builder.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

serialVersionUID

public static final long serialVersionUID

See Also:

Constant Field Values

Constructor Detail

PreferenceDomain

public PreferenceDomain(double min,
                        double max,
                        double prec)

Create a discrete bounded preference domain.

Parameters:

min - The minimum preference value.

max - The maximum preference value.

prec - The preference precision (if 0 or Double.NaN, the domain is continuous).

PreferenceDomain

public PreferenceDomain(double min,
                        double max)

Create a continuous bounded preference domain.

Parameters:

min - The minimum preference value.

max - The maximum preference value.

Method Detail

getMinimum

public double getMinimum()

The minimum preference value.

Returns:

The minimum preference value.

getMaximum

public double getMaximum()

The maximum preference value.

Returns:

The maximum preference value.

hasPrecision

public boolean hasPrecision()

Query whether this preference domain has a precision.

Returns:

true if the domain has a precision for discrete rating values, false if it is continuous.

getPrecision

public double getPrecision()

The precision of preference values. This is the precision with which data is collected from the user — in a 1-5, half-star rating system, it will be 0.5.

Returns:

The preference precision; the return value is undefined if the preference domain has no precision.

See Also:

hasPrecision()

clampValue

public double clampValue(double v)

Clamp a value to this preference domain.

Parameters:

v - The value to clamp.

Returns:

The value, restricted to be in the range [minimum,maximum].

clampVector

public void clampVector(MutableSparseVector vec)

toString

public String toString()

Overrides:

toString in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object o)

Overrides:

equals in class Object

fromString

@Nonnull
public static PreferenceDomain fromString(@Nonnull
                                                   String spec)

Parse a preference domain from a string specification.

Continuous preference domains are specified as [min, max]; discrete domains as min:max[/prec/. For example, a 0.5-5.0 half-star rating scale is represented as [0.5, 5.0]/0.5.

Parameters:

spec - The string specifying the preference domain.

Returns:

The preference domain represented by spec.

Throws:

IllegalArgumentException - if spec is not a valid domain specification.

newBuilder

public static PreferenceDomainBuilder newBuilder()

Create a new preference domain builder.

Returns:

A new preference domain builder.