xtable package: Skipping some rows in the output

Question

In the xtable output, if I want some rows to have nothing in them I will put NA's in the elements of the matrix that correspond to the row that I want skipped.

However this will lead to xtable output of something like & & & & & & & & \\. What I want to know is how do I make it so it's ONLY \\ for that row that I wish to skip.

I don't think you can trick xtable into doing that. As a matter of interest: Why? — vaettchen
Because I generate a HUGE number of tables in my work. My method of doing so is in notepad++ where I have the rownames ready at the top of my .txt, and at the bottom of the .txt I copy my ~80 rows of xtable output, hold down alt (highlighting the table), cut (ctrl+X), go to the top of the .txt, left click on the right of the top-most rowname, spacebar 20 times, then CTRL+V. This way I can construct a very large table automatically with all the multicolumns in place. Except the &&&& get in the way because \multicolumn takes up too many columns. — Jase
If you don't know how to do it, then how can I edit the xtable() function? If I can edit the function then at the very end I can do a grep() search for & & & & and replace the rows (maybe). — Jase
You find the source code here. You could remove those empty rows entirely in R before print( xtable( x ) ) but you need the double backslash? — vaettchen
No, I don't. At each multicolumn spot I can put \\ after it in the template rownamnes. — Jase

vaettchen vaettchen · Accepted Answer · 2012-10-07T08:27:02

Still not sure whether I understand right but I give it a shot.

The most important assumption I'm making here is that your multicolumn rows in that template are always at the same spot. You use R to create a matrix or dataframe with no (useful) data in these rows.

For the purpose of this example, the multicolumn rows are 15, 30 and 60 of a dataframe of 80 rows, corresponding to your template of 80 rows.

What you could do: In R, eliminate those NA rows entirely, so that our dataframe now has only 77 rows.

You insert empty rows for your template via xtable with

> addtorow <- list()
> addtorow$pos <- list()
> addtorow$pos[[1]] <- c(14,29,59)
> addtorow$command <- "\\\\ \n"
> print( xtable( o ), add.to.row = addtorow, include.rownames=FALSE )

That should give you empty lines, no & but with \\ and thus be what you are looking for?

xtable package: Skipping some rows in the output

2 Answers