R help - Jan 2012 - CairoPDF and greek letter spacing

I have a small problem with R graphics output. When I use the lattice
package and CairoPDF to generate publication quality graphs I often use
the expression to create an axis title that has microlitres or
micrometers as a unit. I use something like the following
'expression(paste("Length (", mu,"m )"))' as an
argument to the xlabel
function. The command works but the mu and 'm' have a space between
them. It looks like 'u m' rather than 'um'. It only seems to
happen with
the CairoPDF output on my linux machine, it's fine on the X11 device.
I've fixed it in the past by importing the pdf into inkscape and
manually adjusting the spacing (it's more difficult than it sounds
because I can't actually adjust the spacing but have to delete the mu
and re-enter it).  Is there something I'm doing wrong? Is this a known
bug?  How can I fix it?

-- 
John Walker
Assistant Professor of Cardiology
Department of Medicine
University of Colorado Health Sciences Center
RC2 Room 8412
12700 East 19th Ave B139
Aurora, CO 80045
Office: 303 724 4545

On 10/01/12 11:40, John Walker wrote:
> I have a small problem with R graphics output. When I use the lattice
> package and CairoPDF to generate publication quality graphs I often use
> the expression to create an axis title that has microlitres or
> micrometers as a unit. I use something like the following
> 'expression(paste("Length (", mu,"m )"))' as an
argument to the xlabel
> function. The command works but the mu and 'm' have a space between
> them. It looks like 'u m' rather than 'um'. It only seems
to happen with
> the CairoPDF output on my linux machine, it's fine on the X11 device.
> I've fixed it in the past by importing the pdf into inkscape and
> manually adjusting the spacing (it's more difficult than it sounds
> because I can't actually adjust the spacing but have to delete the mu
> and re-enter it).  Is there something I'm doing wrong? Is this a known
> bug?  How can I fix it?
I can't help, but I can confirm the problem, for what *that* is worth.

It seems be an unfortunate interaction between lattice graphics and
the cairo_pdf() device.

The space between the "mu" and the "m" does not appear with
``ordinary'' R graphics, irrespective of device, nor does it appear
with lattice graphics and, e.g. the pdf() device.  But it does appear
with lattice graphics *and* the cairo_pdf() device.

That probably means that the problem is subtle and will be difficult
to impossible to fix. :-(

Good luck.

     cheers,

         Rolf Turner