(Builds on: List columns, R Markdown basics)
So far you’ve turned .Rmd files into fully-fleshed reports using
RStudio. It is also useful to know how to do so programmatically so that
you can automate your R Markdown workflow. This is particularly useful
in conjunction with parameterised reports and purrr::pwalk().
This technique isn’t discussed frequently, but I think it’s extremely powerful. It might stretch your brain a bit, and you might not understand exactly how it works, but it’s useful pattern to know.
http://rmarkdown.rstudio.com/developer_parameterized_reports.html.
Focus particularly on the “passing parameters” section as that shows how to
call rmarkdown::render(), which is the code equivalent of the “knit”
button in RStudio.
Mapping over multiple arguments [r4ds-21.7]
Walk [r4ds-21.8].
The purrr function we’re going to use is pwalk(). It isn’t described in
detail in R4DS but it’s a combination of pmap() and walk().
YAML header [r4ds-27.6]. Read only §27.6.1; you can skip §27.6.2 for now.