R help - Aug 2001 - Axis labels

Hi,

I am trying to label the x-axis of some histograms with the units of
measurement.

However, when I use, for example:
> truehist(Ca, prob=FALSE, col="gray",
xlab=expression(paste("Calcium
(", mu, eq^-1, ")")))

I get the following message:

Error in eval(expr, envir, enclos) : Object "mu" not found

Could someone let me know what I'm doing wrong?

Many thanks

Gav
> version
         _              
platform i386-pc-mingw32
arch     x86            
os       Win32          
system   x86, Win32     
status                  
major    1              
minor    3.0            
year     2001           
month    06             
day      22             
language R 

Win2000

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Gavin Simpson wrote:
> 
> Hi,
> 
> I am trying to label the x-axis of some histograms with the units of
> measurement.
> 
> However, when I use, for example:
> 
> > truehist(Ca, prob=FALSE, col="gray",
xlab=expression(paste("Calcium
> (", mu, eq^-1, ")")))
> 
> I get the following message:
> 
> Error in eval(expr, envir, enclos) : Object "mu" not found
> 
> Could someone let me know what I'm doing wrong?

truehist (which is in the package MASS !):

function(   ...   )
{
  eval(xlab)
  ...

So the first line in the body of truehist() causes your problem.
You don't need this line in your case, I think. So just create your own
function without this line.  Maybe the author of the function can help
more precisely.

Uwe Ligges
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