Space in output_dir in rmarkdown::render()

[phargarten2]

Using pdflatex, I ran into a problem compiling when output_dir had spaces in the filename rmarkdown::render(). pdflatex() gave the error Undefined control sequence. I realize that the file cannot be found due to a space in output_dir.

This problem has been well documented
https://stackoverflow.com/questions/57061618/error-generating-pdf-document-with-rmarkdown-when-output-dir-contains-spaces
#1285 (comment)
although pdflatex is somewhat more tolerant of spaces in the past.

       rmarkdown::render(
         input = "lab-specific-report.Rmd",    #name of child R Markdown file
         output_dir = "my_folder/pgm name/doc",  #Latex Fails with spaces 
         output_file = "My_File_1_Week_1",
         output_format = "pdf_document",
       )

Upon compiling, LaTex pdflatex gave this error:

Undefined control sequence
LaTeX Font Info:    Trying to load font information for T1+lmtt on input line 9
3.
(c:/Users/ph137/AppData/Roaming/TinyTeX/texmf-dist/tex/latex/lm/t1lmtt.fd
File: t1lmtt.fd 2015/05/01 v1.6.1 Font defs for Latin Modern
)

! Undefined control sequence.
 ...rmessage  LaTeX Error: File `my_folder/pgm name/doc
l.99 ..._/figure-latex/report-plots-1}
                                                   \end{center} 
Here is how much of TeX's memory you used:
 12231 strings out of 480954
 185972 string characters out of 5905841
 511514 words of memory out of 5000000
 29269 multiletter control sequences out of 15000+600000
 413278 words of font info for 37 fonts, out of 8000000 for 9000
 14 hyphenation exceptions out of 8191
 85i,3n,88p,668b,328s stack positions out of 5000i,500n,10000p,200000b,80000s

!  ==> Fatal error occurred, no output PDF file produced!

After reviewing Yui's comments (see #1285 (comment)), I suggest to add a warning in rmarkdown::render() indicating that the spaces in the filenames may cause LaTex to fail its compilation, maybe in pdflatex, but definitely in xelatex. Add something like this in the function:

if(length(grep(" ", output_dir, fixed = TRUE)) > 0){
  warning("The output directory contains a space. LaTex may have trouble finding files. Suggest to remove space if possible.",
          call. = FALSE)
} 

Other suggestions include using a relative directory (which I am not a fan of) or a temporary drive, but spaces throw off LaTex. I am not sure what to do if you can't remove spaces from the filename.

[cderv]

Thanks for the report.

What about rendering the Rmd file where it lives (so not setting output_dir with a space in the path) and maybe move the rendered file after ?

This way the output directory should not impact the pdf rendering, is it ?

[phargarten2]

Thank you. Yes, great idea. I agree that your comment should work. So you mean to set output_dir to its default, NULL (and move the rendered file after)?

Yet, if render() could warn a user that a space in output_dir exists, I think that would help the user identify the source of the problem, as the LaTex undefined control sequence error is often difficult to diagnose.

[cderv]

We could try add a warning for this. All the file input like output_dir, output_file, intermediate_dir, ... could be sensible to things like that and it is hard to know beforehand.

We could start with small step by adding a warning when we know this is necessary. Thanks for the suggestion !