tables in pander, style="multiline"

Question

I'm using RStudio 0.98.1056 on Windows 7, and whatever the current version of pander is on CRAN as of today (I just installed the package).

I'm trying to use the knitr->Markdown->.docx literate-programming workflow to create a table in Word. Some of the cells need to contain hard line breaks. I believe this should be possible based on info in the following link:

http://rmarkdown.rstudio.com/authoring_pandoc_markdown.html

It says, "A backslash followed by a newline is also a hard line break. Note: in multiline and grid table cells, this is the only way to create a hard line break, since trailing spaces in the cells are ignored."

I'm trying to create a table with cells containing line breaks in the following way:

library(pander)
a <- c(1:10)
b <- c(11:20)
ab <- paste(a,b,sep='\n')
N <- ceiling(rpois(10,9))
labels <- paste("Question",c(1:10))
mytable <- data.frame(labels,ab,N)
pandoc.table(mytable, style="multiline")

But the newline just gets stripped. Same if I use sep="< newline>" or sep="< br>" (without leading spaces). I have also tried adding an extra backslash, in case R was "eating" the first one; and switching up the "paste" function to include each of these possible separators as a term in their own right, instead of in the sep= argument. None of these things worked.

I went to try out the example code in the pander help documentation, just as a sanity check, and it seems the issue is general -- sample code that I thought should produce multiline tables did not, on my machine.

Has anyone else gotten multiline tables in pander to work?

Febrile

Answer 1

Yup, please install the development version from GitHub -- this issue was fixed a few months ago. E.g.:

> panderOptions('keep.line.breaks', TRUE)
> pander(mytable)

--------------------
labels      ab   N  
----------- ---- ---
Question 1  1    11 
            11      

Question 2  2    6  
            12      

Question 3  3    13 
            13      

Question 4  4    12 
            14      

Question 5  5    6  
            15      

Question 6  6    6  
            16      

Question 7  7    11 
            17      

Question 8  8    19 
            18      

Question 9  9    10 
            19      

Question 10 10   9  
            20      
--------------------

Breaststroke

Thanks for this. I got the devel version of pander installed (after resolving some issues with Rtools), and when I run pander(mytable) I get the same output you saw in R. On the other hand, that output doesn't knit properly to either HTML or docx: the linebreaks are removed. What am I missing? I'm still using pandoc.table(mytable, style="multiline") instead of the simpler syntax, so that's not the issue. I've also tried with style="grid": no dice. – Febrile

@ErinMcJ that's a Pandoc issue. Quote from its documentation: "A backslash followed by a newline is also a hard line break. Note: in multiline and grid table cells, this is the only way to create a hard line break, since trailing spaces in the cells are ignored." So you not only need to add the manual line breaks (\n), but also a hard line break. See a demo by running pander(descr::CrossTable(mtcars$am, mtcars$gear), split.table = Inf) – Breaststroke

Aha! Yes! I was really confused about what a hard line break is, if it isn't the backslash-n sequence. But it turns out that in order for \\n to render appropriately, I needed an extra backslash as an escape character: so, \\\n. – Febrile