QUDTLib: Java Unit Conversion Library based on QUDT

Provides unit conversion and related functionality for Java.

Makes all conversions and related functionality defined by the excellent QUDT ontology available in a self-contained jar with no external dependencies. The jar containing all dependencies is ~400kB large.

The library offers

• 1745 units, such as second, Fahrenheit, or light year
• 881 quantityKinds, such as width, pressure ratio or currency
• 29 prefixes, such as mega, kibi, or atto

...all of which the library converts if possible.

Usage

The module clients will want to use is io.github.qudtlib:qudtlib. The other modules are merely needed to generate that one from either a QUDT release zip or a QUDT repository branch/tag/revision.

By default, the project uses the release zip configured in the project's qudt.release.version property.

If the environment variable scmVersion is set (e.g. by building with mvn install -DscmVersion=main), the QUDT repository's branch with the specified name is used.

To build from a tag in the QUDT repo, use e.g. -DscmVersionType=tag -DscmVersion=v2.1.33

To build from a revision in the QUDT repo use e.g. -DscmVersionType=revision -DscmVersion=c4456d5

Maven dependency:

<dependency>
	<groupId>io.github.qudtlib</groupId>
	<artifactId>qudtlib</artifactId>
	<version>${project.version}</version> <!-- remember to use the latest version -->
	<type>pom</type>
</dependency>

API

io.github.qudtlib.Qudt is your friend. All functionality is accessed through static methods of that class. You can explore the API from that starting point.

The main Model classes are:

• Unit: encapsulates IRI, label, dimension vector, multiplier/offset, factor units (if any). Descriptions are omitted (create an issue if you want them.)
• QuantityKind: IRI, label, applicable units, broader quantity kinds
• QuantityValue: value and unit. Values are always BigDecimal (using MathContext.DECIMAL128) and there are no convenience methods allowing you to provide other numeric types. This is intentiaonal so as not to mask any conversion problems. You'll be fine. (If you need a different MathContext, make an issue)

All units, quantityKinds and prefixes are avalable as constants:

• Qudt.Units: all units, such as Qudt.Units.KiloM__PER__SEC
• Qudt.QuantityKinds:: all quantityKinds, such as Qudt.QuantityKinds.BloodGlucoseLevel
• Qudt.Prefixes: all prefixes, such as Qudt.Prefixes.Atto

The functionality comprises:

• Qudt.convert(...): Convert a value
• Qudt.scaledUnit(...): Scale a unit (e.g., make KiloM from M and kilo)
• Qudt.unscaledUnit(..): Unscale a unit:
• Qudt.unit(...): Get Unit by IRI
• Qudt.quantityKind(...): Get QuantityKind by IRI
• Qudt.unitFromLocalName(...): Get Unit by local name (i.e., last part of IRI)
• Qudt.quantityKindFromLocalName(...): Get QuantityKind by local name (i.e., last part of IRI)
• Qudt.derivedUnitsFrom...(...): Get Units by 'factor units', e.g. find N for factors m, kg, and s^-2. Different matching modes available for broader or narrower matching.
• Qudt.unitFromLabel(...): Get Unit by label

Examples

(see also module qudtlib-example)

Unit conversion

Converting 38.5° Celsius into Fahrenheit:

Qudt.convert(new BigDecimal("38.5"), Qudt.Units.DEG_C, Qudt.Units.DEG_F));
-->
101.3 unit:DEG_F

Find unit by factor units

Finding unit for factors: m, kg, and s^-2:

Set<Unit> myUnits =
          Qudt.derivedUnitFromUnitExponentPairs(
                        Qudt.Units.M, 1,
                        Qudt.Units.KiloGM, 1,
                        Qudt.Units.SEC, -2);
-->
N

Find factor units of a derived unit:

Finding factors of unit N:

List<FactorUnit> myFactorUnits = Qudt.Units.N.getFactorUnits();
-->
FU{m^1}
FU{kg^1}
FU{s^-2}

Scale Conversion

Converting 1N into kN:

QuantityValue quantityValue = new QuantityValue(new BigDecimal("1"), Qudt.Units.N);
QuantityValue converted = Qudt.convert(quantityValue, Qudt.Units.KiloN);
-->
0.001kN

List convertible units

Which units can we convert to from L?

Unit fromUnit = Qudt.Units.L;
for (Unit unit : Qudt.allUnits()) {
     if (Qudt.isConvertible(fromUnit, unit)) {
          System.out.println("  " + unit + " (" + unit.getIri() + ")");
     }
}
-->
unit:GT (http://qudt.org/vocab/unit/GT)
tsp (http://qudt.org/vocab/unit/TSP)
cup (http://qudt.org/vocab/unit/CUP)
unit:YD3 (http://qudt.org/vocab/unit/YD3)
RT (http://qudt.org/vocab/unit/RT)
unit:M3 (http://qudt.org/vocab/unit/M3)
fL (http://qudt.org/vocab/unit/FemtoL)
dry_pt (http://qudt.org/vocab/unit/PINT_US_DRY)
daL (http://qudt.org/vocab/unit/DecaL)
pL (http://qudt.org/vocab/unit/PicoL)
unit:CUP_US (http://qudt.org/vocab/unit/CUP_US)
hL (http://qudt.org/vocab/unit/HectoL)
ML (http://qudt.org/vocab/unit/MegaL)
unit:BBL_US (http://qudt.org/vocab/unit/BBL_US)
st (http://qudt.org/vocab/unit/STR)
oz (http://qudt.org/vocab/unit/OZ_VOL_US)
unit:OZ_VOL_UK (http://qudt.org/vocab/unit/OZ_VOL_UK)
dL (http://qudt.org/vocab/unit/DeciL)
dry_gal (http://qudt.org/vocab/unit/GAL_US_DRY)
tbsp (http://qudt.org/vocab/unit/TBSP)
unit:Standard (http://qudt.org/vocab/unit/Standard)
nL (http://qudt.org/vocab/unit/NanoL)
unit:MilliM3 (http://qudt.org/vocab/unit/MilliM3)
gal (http://qudt.org/vocab/unit/GAL_IMP)
qt (http://qudt.org/vocab/unit/QT_US)
unit:PlanckVolume (http://qudt.org/vocab/unit/PlanckVolume)
pk (http://qudt.org/vocab/unit/PK_US_DRY)
unit:PK_UK (http://qudt.org/vocab/unit/PK_UK)
mL (http://qudt.org/vocab/unit/MilliL)
μL (http://qudt.org/vocab/unit/MicroL)
unit:DeciM3 (http://qudt.org/vocab/unit/DeciM3)
pt (http://qudt.org/vocab/unit/PINT_US)
unit:PINT_UK (http://qudt.org/vocab/unit/PINT_UK)
Bf (http://qudt.org/vocab/unit/FBM)
pi (http://qudt.org/vocab/unit/PINT)
unit:GAL_UK (http://qudt.org/vocab/unit/GAL_UK)
gal (http://qudt.org/vocab/unit/GAL_US)
bbl (http://qudt.org/vocab/unit/BBL)
unit:MicroM3 (http://qudt.org/vocab/unit/MicroM3)
ac-ft (http://qudt.org/vocab/unit/AC-FT)
unit:FT3 (http://qudt.org/vocab/unit/FT3)
unit:QT_UK (http://qudt.org/vocab/unit/QT_UK)
unit:CentiM3 (http://qudt.org/vocab/unit/CentiM3)
bui (http://qudt.org/vocab/unit/BU_UK)
bua (http://qudt.org/vocab/unit/BU_US)
unit:MI3 (http://qudt.org/vocab/unit/MI3)
unit:BBL_US_DRY (http://qudt.org/vocab/unit/BBL_US_DRY)
kL (http://qudt.org/vocab/unit/KiloL)
unit:BBL_UK_PET (http://qudt.org/vocab/unit/BBL_UK_PET)
unit:IN3 (http://qudt.org/vocab/unit/IN3)
dry_qt (http://qudt.org/vocab/unit/QT_US_DRY)
L (http://qudt.org/vocab/unit/L)
cL (http://qudt.org/vocab/unit/CentiL)
unit:DecaM3 (http://qudt.org/vocab/unit/DecaM3)
unit:TON_SHIPPING_US (http://qudt.org/vocab/unit/TON_SHIPPING_US)
unit:GI_UK (http://qudt.org/vocab/unit/GI_UK)
unit:GI_US (http://qudt.org/vocab/unit/GI_US)
C (http://qudt.org/vocab/unit/CORD)

List applicable Units for a QuantityKind:

Which units are applicable for PressureRatio?

for (String unitIri : Qudt.QuantityKinds.PressureRatio.getApplicableUnits()) {
     Unit unit = Qudt.unit(unitIri);
     System.out.println("  " + unit + " (" + unit.getIri() + ")");
}
-->
unit:MegaPA-PER-BAR (http://qudt.org/vocab/unit/MegaPA-PER-BAR)
unit:HectoPA-PER-BAR (http://qudt.org/vocab/unit/HectoPA-PER-BAR)
unit:PA-PER-BAR (http://qudt.org/vocab/unit/PA-PER-BAR)
unit:KiloPA-PER-BAR (http://qudt.org/vocab/unit/KiloPA-PER-BAR)
unit:MilliBAR-PER-BAR (http://qudt.org/vocab/unit/MilliBAR-PER-BAR)
unit:PSI-PER-PSI (http://qudt.org/vocab/unit/PSI-PER-PSI)
unit:BAR-PER-BAR (http://qudt.org/vocab/unit/BAR-PER-BAR)

Instantiate unit by its label

Instantiating unit by label 'Pint (UK)':

Qudt.unitFromLabel("Pint (UK)"));
-->
unit:PINT_UK

Acknowledgments

This project has been developed at the Research Studio Smart Application Technologies in the project ‘BIM-Interoperables Merkmalservice’, funded by the Austrian Research Promotion Agency and Österreichische Bautechnik Veranstaltungs GmbH.