Pandoc is used to generate a PDF from an R markdown document that has a chunk that generates a plot using ggplot2 and a custom function, progress.plot.  The chunk looks like this

The PDF is generated using a LaTeX engine.  I think it uses PDFlatex via pandoc.  This is causing a problem that appears to be close to the pandoc metal.

It seems like pandoc uses a temporary folder to store the diagram I generate with ggplot2.  The name of that folder has as underscore.  This means the path to the graphic file, a string that's used in the .tex source file, has an underscore.  And the latex compiler doesn't like that.

The "_files" in the latex log snippet, above, is the name of a folder created by pandoc (or Rmarkdown).  I am getting a "Missing $ inserted" error before the latex compiler craps out.  No PDF is generated and the directory with the figure is deleted.

Is there a pandoc configuration change to take the underscore out of the temporary directory's name?  Or is there any other workaround that will allow me to generate figures to include in my R markdown document?

Thanks for whatever advice people can share.