org.das2.datum

Class UnitsUtil

java.lang.Object

org.das2.datum.UnitsUtil

public final class UnitsUtil
extends java.lang.Object

Useful operations for units, and tests for Steven's Levels of Measurement.

See Also:

http://www.statisticssolutions.com/data-levels-of-measurement/

Method Summary

Modifier and Type	Method and Description
static Datum	divide(Datum aDatum, Datum bDatum) attempt to perform the division of two Datums by looking for convertible units or dimensionless.
static java.lang.String	divideToString(Datum aDatum, Datum bDatum) Special division operation that either does the Datum division if possible, or returns the division of the magnitude parts of the Datums plus the unit names "A/B", suitable for human consumption.
static Units	getInverseUnit(Units unit) returns the unit whose product with the parameter unit is unity.
static boolean	isIntervalMeasurement(Units unit) returns true if the unit is a interval measurement, meaning the choice of zero is arbitrary.
static boolean	isIntervalOrRatioMeasurement(Units unit) returns true if the unit is a interval measurement or is a ratio measurement, and not a nominal or ordinal measurement.
static boolean	isNominalMeasurement(Units unit) returns true if the unit is nominal, meaning that Datums with this unit can only be equal or not equal.
static boolean	isOrdinalMeasurement(Units unit) returns true if the unit is ordinal, meaning that Datums with this unit can only be equal or not equal, or compared.
static boolean	isRatioMeasurement(Units unit) returns true if the unit is a ratio measurement, meaning there is a physical zero and you can make meaningful ratios between arbitrary numbers.
static boolean	isRatiometric(Units unit) returns true if the unit is used to measure distance in a logarithmic space, such as decibels or percent increase.
static boolean	isTimeLocation(Units unit) returns true if the unit describes a location in time, as in us2000 or Units.lookupTimeUnits('seconds since 1989-12-13T00:00Z')

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

isRatiometric

public static boolean isRatiometric(Units unit)

returns true if the unit is used to measure distance in a logarithmic space, such as decibels or percent increase. Note Units.dimensionless are not considered ratiometric. (Of course, all ratiometic units are dimensionless...) Do not confuse this with isRatioMeasurement. "5kg" is ratio measurement. "105%" is ratiometric.

Parameters:

unit - the unit

Returns:

true if the unit is used to measure distance in a logarithmic space

isTimeLocation

public static boolean isTimeLocation(Units unit)

returns true if the unit describes a location in time, as in us2000 or Units.lookupTimeUnits('seconds since 1989-12-13T00:00Z')

Parameters:

unit - the unit to test

Returns:

true if the unit describes a location in time

isRatioMeasurement

public static boolean isRatioMeasurement(Units unit)

returns true if the unit is a ratio measurement, meaning there is a physical zero and you can make meaningful ratios between arbitrary numbers. All operations like add, multiply and divide are allowed. Examples include "5 km" or "0.2/cc" and "15 counts"

Parameters:

unit -

Returns:

See Also:

http://en.wikipedia.org/wiki/Level_of_measurement, http://www.statisticssolutions.com/data-levels-of-measurement/, https://www.questionpro.com/blog/nominal-ordinal-interval-ratio/

isIntervalMeasurement

public static boolean isIntervalMeasurement(Units unit)

returns true if the unit is a interval measurement, meaning the choice of zero is arbitrary. Subtraction and comparison are allowed, but addition, multiplication and division are invalid operators. Examples include "2008-04-09T14:27:00Z" and 15 deg W Longitude.

Parameters:

unit -

Returns:

See Also:

http://en.wikipedia.org/wiki/Level_of_measurement, http://www.statisticssolutions.com/data-levels-of-measurement/

isIntervalOrRatioMeasurement

public static boolean isIntervalOrRatioMeasurement(Units unit)

returns true if the unit is a interval measurement or is a ratio measurement, and not a nominal or ordinal measurement. These are things that are plotted by showing a location on an axis. See http://en.wikipedia.org/wiki/Level_of_measurement Examples include "2008-04-09T14:27:00Z" and "5 km"

Parameters:

unit -

Returns:

isNominalMeasurement

public static boolean isNominalMeasurement(Units unit)

returns true if the unit is nominal, meaning that Datums with this unit can only be equal or not equal. Currently all nominal data is stored as ordinal data, so this always returns false. Examples include "Iowa City", and "Voyager 1". See http://en.wikipedia.org/wiki/Level_of_measurement

Parameters:

unit - the unit

Returns:

true if the unit is nominal.

isOrdinalMeasurement

public static boolean isOrdinalMeasurement(Units unit)

returns true if the unit is ordinal, meaning that Datums with this unit can only be equal or not equal, or compared. subtract, add, multiply, divide are invalid. Examples include energy bin labels and quality measures. See http://en.wikipedia.org/wiki/Level_of_measurement

Parameters:

unit -

Returns:

true if the unit is ordinal.

getInverseUnit

public static Units getInverseUnit(Units unit)

returns the unit whose product with the parameter unit is unity. (Presently this is only supports time units like Hz→seconds).

Parameters:

unit - the unit

Returns:

the inverse unit, or throws exception if one is not known.

Throws:

java.lang.IllegalArgumentException - if the units inversion is not known.

divideToString

public static java.lang.String divideToString(Datum aDatum,
                                              Datum bDatum)

Special division operation that either does the Datum division if possible, or returns the division of the magnitude parts of the Datums plus the unit names "A/B", suitable for human consumption.

Parameters:

aDatum - the numerator

bDatum - the denominator

Returns:

String for the result, or "A/B"

divide

public static Datum divide(Datum aDatum,
                           Datum bDatum)

attempt to perform the division of two Datums by looking for convertible units or dimensionless.

Parameters:

aDatum - the numerator

bDatum - the denominator

Returns:

the result