On Thu, 5 Feb 2009, cls59 wrote:
Hello Everyone,
I am an avid Sweave user and I am trying to pretty print floating point
numbers for latex output. For example in my document, I would like:
4.2\cdot 10^-{8}
Instead of:
4.2e-08
The Hmisc package has a nice function for doing this- but Hmisc has a ton of
dependencies and has proved very unportable to the various machines I work
on. So, I set out to write my own function that just uses basic R commands,
it looks like this:
latexNum <- function (x,dig=4,sci=T)
{
x <- format(x,digits=dig,scientific=sci)
x <- gsub("e\\+00","",x)
x <- gsub("e\\-0([0-9]*)","\\\\cdot 10^{-\\1}",x)
x <- gsub("e\\-([0-9]*)","\\\\cdot 10^{-\\1}",x)
x <- gsub("e\\+0([0-9]*)","\\\\cdot 10^{\\1}",x)
x <- gsub("e\\+([0-9]*)","\\\\cdot 10^{\\1}",x)
return(x)
}
Everything works nicely, if I type
latexNum(4*10^-3)
I get
[1] "4\\cdot10^{-3}"
And the following:
cat(latexNum(4*10^-3))
Produces:
4\cdot10^{-3}
However the following in a .Rnw file:
$\Sexpr{latexNum(4*10^-3)}$\\
The syntax Sweave uses is fairly sensitive to backslashes. I might guess
that this is a feature to protect against runaway expressions.
You need to add a backslash to undo what Sweave does to the backslashes in
that type of expression.
Put
extra.slash <- function(x) sub('\\','\\\\', x, fixed=TRUE)
in an earlier code chunk and then call
\Sexpr(extra.slash( latexNum( 4*10^3 ) ) )
or better still just use a code chunk like this:
@
<<echo=F,results=tex>>
cat( latexNum( 4*10^3 ) )
@ %def
HTH,
Chuck
Only produces this in the .tex output file:
$4cdot 10^{-3}$\\
No amount of extra backslashing seems to help. Any idea why my escapes are
not being respected?
-----
Charlie Sharpsteen
Undergraduate
Environmental Resources Engineering
Humboldt State University
--
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Charles C. Berry (858) 534-2098
Dept of Family/Preventive Medicine
E mailto:cbe...@tajo.ucsd.edu UC San Diego
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