Create parametric R markdown documentation?

Question

I want to iterate over a list of result-sets in my R markdown file. When I produce the output I want to include some text like headers with the name of the result set.

One hacky solution I have found is to hardcode the html output directly in the documentation like this

## All results

```{r loopResults, echo=FALSE, results='asis'}
results = list(result1 = data.frame(x=rnorm(3), y=rnorm(3)), result2=data.frame(x=rnorm(3), y=rnorm(3)))

for(res in names(results)) {
  cat(paste("<h3>Results for: ", res, "</h3>>"))

  plot(results[[res]]$x, results[[res]]$y)
}

This doesn't seem to be the right way to do things, especially since I want to create PDF documents via pandoc at time and would have to change the hard-coded expressions. (I have currently convenience functions like h3(text, type)).

Is there a better way of doing this?

Answer 1

I would use a combination of brew and knitr to achieve this. I would create a brew template called doc.brew which looks like this

<% for (res in names(results)) { -%>

### Results for: <%= res %>

```{r}
plot(results[["<%= res %>"]]$x, results[["<%= res %>"]]$y)
```

<% } %>

You can now run the following code to get your desired output

results = list(
  result1 = data.frame(x=rnorm(3), y=rnorm(3)), 
  result2=data.frame(x=rnorm(3), y=rnorm(3))
)
brew::brew('doc.brew', 'doc.Rmd')
knit2html('doc.Rmd')