How to extract dependencies from an Rmarkdown document

Question

I need to re-knit a long Rmarkdown document (about 3k lines.). But the author used some packages that I don't have. So I need to install them first.

Is there any way to save all or some of my efforts to manually check the whole document?

Answer 1

purl() will extract all the R chunks, and you could grep() for packages there.