There appears to be no fast and easy way to extract the R code from HTML files generated via R Markdown.

Example

Max and Davis's applied-ml workshop is a good example.

We can easily get the R code for 'Part_1.html', since we have access to the original .Rmd file, and can hence call

knitr::purl("Part_1.Rmd")
readLines("Part_1.R") %>% paste0(collapse="\n\n") %>% cat
# Displays R code...

But we cannot so easily get the R code for parts 2 through 5, as the originating .Rmd is not available.

Possible solution

html_to_r() extracts the R code from R Markdown generated HTML files.

I provide an implementation in a PR.

Using in the applied-ml example

We can now easily retrieve the R code from the .html files, like so

# from inside applied-ml
dir() %>% grep("Part_{1}.*html", ., value = T) %>% sapply(., html_to_r) -> a
dir() %>% grep("Part_{1}.*html", ., value = T) %>% mapply(html_to_r, inc_out=F, .) -> b

# Randomly inspect the second file with / without output to ensure it worked as expected
a[[2]] %>% cat # with output
b[[2]] %>% cat # without output

This can be merged if relevant or disregarded if not relevant.