You are on the right track, but I am a bit confused: do you want the selected rows highlighted by hline
and rowcolor
? In my experience, rowcolor alone looks better, so I will assume that in my answer below (but you could easily use both, just append the \\hline
command).
As a bonus, all code below assumes you use the LaTeX booktabs
package, which gives correctly weighted rules (unlike hline). To be honest, I always work with booktabs, and I couldn't bother to adjust the code to use hline -- but if you prefer hline, replace all \toprule
, \midrule
and \bottomrule
macros with \hline
.
You seem to have missed that LaTeX longtables require a special header, and we need to supply that too as an element to the command
vector of the add.to.row
list (this may be the reason your typeset table looks bad).
longtable.xheader <-
paste("\\caption{Set your table caption.}",
"\\label{tab:setyourlabel}\\\\ ",
"\\toprule ",
attr(xtable(mydf), "names")[1],
paste(" &", attr(xtable(mydf), "names")[2:length(attr(xtable(mydf), "names"))], collapse = ""),
"\\\\\\midrule ",
"\\endfirsthead ",
paste0("\\multicolumn{", ncol(xtable(mydf)), "}{c}{{\\tablename\\ \\thetable{} -- continued from previous page}}\\\\ "),
"\\toprule ",
attr(xtable(mydf), "names")[1],
paste("&", attr(xtable(mydf), "names")[2:length(attr(xtable(mydf), "names"))], collapse = ""),
"\\\\\\midrule ",
"\\endhead ",
"\\midrule ",
paste0("\\multicolumn{", as.character(ncol(xtable(mydf))), "}{r}{{Continued on next page}}\\\\ "),
"\\bottomrule \\endfoot ",
"\\bottomrule \\endlastfoot ",
collapse = "")
With that taken care of, go ahead and print
the xtable:
print(xtable(mydf),
floating = FALSE, % since longtable never floats
hline.after = NULL, % hline off since I use booktabs
add.to.row = list(pos = list(-1,
c(0, 2),
nrow(xtable(mydf))),
command = c(longtable.xheader,
"\\rowcolor[gray]{0.75}\n",
"%")), % comments out a spurious \hline by xtable
include.rownames = FALSE, % depends on your preference
include.colnames = FALSE, % depends on your preference
type = "latex",
tabular.environment = "longtable",
% xtable tries to escape TeX special chars, can be annoying sometimes
sanitize.text.function = function(x){x},
% not all dashes are meant to be math negative sign, set according to your data
math.style.negative = FALSE)
I hope my use of booktabs in the answer did not confuse you too much.
Keep knitting!