Measurement Units in R

Authors

Edzer Pebesma, Institute for Geoinformatics
Thomas Mailund, Aarhus University
James Hiebert, University of Victoria

Date of this Version

12-2016

Document Type

Article

Citation

The R Journal (December 2016) 8(2); Editor: Michael Lawrence

Comments

Copyright 2016, The R Foundation. Open access material. License: CC BY 3.0 Unported

Abstract

We briefly review SI units, and discuss R packages that deal with measurement units, their compatibility and conversion. Built upon udunits2 and the UNIDATA udunits library, we introduce the package units that provides a class for maintaining unit metadata. When used in expression, it automatically converts units, and simplifies units of results when possible; in case of incompatible units, errors are raised. The class flexibly allows expansion beyond predefined units. Using units may eliminate a whole class of potential scientific programming mistakes. We discuss the potential and limitations of computing with explicit units.