colin-fraser / convertR

Unit conversions

Very simple unit conversions package

This package just gives you one function: convert.

Examples

> convert(100, 'lb', 'kg')
[1] 45.35924
> convert(5:10, 'kWh', 'therm')
[1] 0.1706071 0.2047285 0.2388499 0.2729713 0.3070927 0.3412141
> convert(933394, 'km', 'min')
Error in convert(933394, "km", "min") : 
  No conversion path found between units

How does it work?

Inside this package is a forest. The forest looks like this ![Image of a graph] (https://raw.githubusercontent.com/colin-fraser/convertR/master/graph.png)

Along each edge is a conversion factor. When convert(number, from, to) is called, a path is drawn from from to to, and the conversion factors along the path edges are multiplied together. number is multiplied by the product of the conversion factors. That's it.

This design lets convertR make hundreds of different types of unit conversions only knowing a handful of conversion factors.

The unit symbols and conversion factors are taken from this Wikipedia entry.

Installation

At the moment, this requires the package igraph. That's okay, because that's a nice package. Then if you have devtools you can just go devtools::install_github('colin-fraser/convertR').

TODO

• Add more units
• Add English unit aliases
• Maybe remove igraph dependency?