[R] 2 problems with latex.table (quantreg package) - reproducible

[Kati Schweitzer]

Dear all,

When using latex.table from the quantreg package, I don't seem to be able to set
table.env=FALSE: when I don't specify caption (as I think I should, when
understanding the R help rightly(?)), I get an error message, and when I
do so, of course I get one, as well.
The funny thing is, that a table is indeed produced in the first case,
so I get a nice tabular, but as I'm using the command within a for -
loop, the loop stops due to the error and only one latex table is
produced.

Example R-Code:

library(quantreg)

v1 <- c("val1","val1","val2")
v2 <- c("val1","val2","val2")
tab <- table(v1,v2)

latex.table(tab,table.env=FALSE)
#error - german R error message (saying that caption  is missing and
has no default :-) ):
#Fehler in cat(caption, "\n", file = fi, append = TRUE) :
#       Argument "caption" fehlt (ohne Standardwert)

latex.table(tab,table.env=FALSE,caption="nothing")
#error - german R error message:
#Fehler in latex.table(tab, table.env = FALSE, caption = "nothing") :
#       you must have table.env=TRUE if caption is given


The second problem is, that - when using latex.table to produce a
tabular within a table environment - I would like to specify cgroup
with only one value - one multicolumn being a heading for both columns
in the table.
But I'm not able to produce latex-compilable code:

latex.table(tab,cgroup="v2",caption="my table")

gives me the following latex code:
\begin{table}[hptb]
\begin{center}
\begin{tabular}{|l||c|c|} \hline
\multicolumn{1}{|l||}{\bf
tab}&\multicolumn{}{c||}{}&\multicolumn{2}{c|}{\bf v2}\\ \cline{2-3}
\multicolumn{1}{|l||}{}&\multicolumn{1}{c|}{val1}&\multicolumn{1}{c|}{val2}\\
\hline
val1&1&1\\
val2&0&1\\
\hline
\end{tabular}
\vspace{3mm}
\caption{my table\label{tab}}
\end{center}
\end{table}

and within this code the problem is the second multicolumn
(&\multicolumn{}{c||}{}), as it has no number specifying how many
columns the multicolumn should cover. Latex (at least my version)
complains.
When deleting this part of the code, the table is compiled and looks
exactly how I want it to look. I'm doing this with a system call and
an shell script right now, but this seems pretty ugly to me...

When I specify 2 columns, this problem doesn't occur:
latex.table(tab,cgroup=c("blah","v2"),caption="my table")

I'm running R Version 2.3.0 (2006-04-24) on a linux machine Fedora
Core 5 (i386).

Can anyone help me find my mistakes?

Thanks a lot
... and sorry for my bad English and potential newbie mistakes!!
Kati