[R] unit attribute to list elements

[baptiste Auguié]

Hi,

I've started my own (first) package, part of which consists in  
listing common physical constants (Planck's constant, the speed of  
light in vacuum, etc). I'm wondering what would be a good way of  
dealing with pairs of value/unit.


> constants <- list( cel = 2.99792458e8 , #m/s
> Z0 = 376.730313461, #ohm
> eps0 = 8.854187817e-12,#F/m
> mu0 = 4*pi*1e-7,#N/A^2
> G = 6.67428e-11 # m^3 kg-1 s-2
> )


I thought I could include the unit in the names attribute of each  
element, as in :

> names(constants$cel)<- " speed of light in vacuum [m.s^-1]"


Writing this for every element is very redundant... Is there any way  
to access and set the name of each first level element of the list?

> namesFirstLevelElements(constants)<- c(" speed of light in vacuum  
> [m.s^-1]",
> "impedance of vacuum [some unit]",
> ...)


Quite possibly, I'm completely on the wring track;

- maybe such a package already exists

- a custom class or structure would be more appropriate? I don't  
really know how to deal with classes, though, and I'd like to keep  
the access to the constants' values as direct and generic as possible.

Many thanks in advance,

baptiste

_____________________________

Baptiste Auguié

Physics Department
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK

Phone: +44 1392 264187

http://newton.ex.ac.uk/research/emag
http://projects.ex.ac.uk/atto