Optimizing R Markdown workflow - reusing R Markdown chunks with parameters?

Andrea · September 20, 2018, 11:55am

Hmmm. I think you did, but the problem is I don't use child documents, so I can't follow you very well. Still, could parametrized reports help in your case? Now, if you don't share a minimal reproducible example I cannot really understand what's going on (and I cannot test solutions). However, one limit of child documents is that they all share the same enviroment as the main document, unless you do something very special.
To pass parameters to child documents, all sharing a common environment:

gist.github.com

https://gist.github.com/rmoff/a043676a2f084b81a434

00.README.md

When you use `knit_expand` it appears that the inclusion of the Rmd is done on the first pass, and then the complete document evaluated. This means that a Rmd block referenced in loop with `knit_expand` will only evaluate changing variables at their last value. 

This can be worked around by passing the literal value of the variable at the time of the `knit_expand` with `{{var}}` syntax. 

This is documented in the [knitr_expand](https://cran.r-project.org/web/packages/knitr/vignettes/knit_expand.html) docs, but less clear (to an R noob like me) for embedded documents rather than strings.

01.master.Rmd.txt

---
title: "Child test"
output: html_document
---

```{r global_options, include=FALSE}
knitr::opts_chunk$set(echo=FALSE, warning=FALSE,message=FALSE, cache=FALSE)
```

# This is the main heading

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02.child.Rmd.txt

### This is the child code block {{i}}

#### Vanilla

The value of value.to.match called through standard Rmd inline is `r value.to.match`. 

Let's try and do something dynamic, showing flights only for the given origin specified in the variable value.to.match: 

```{r echo=TRUE}
my.data %>%

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To call multiple times the same child document, but each time with different arguments in a different environment:

Note that unfortunately the example is for .Rw (run Sweave) documents, rather than for .Rmd (R Markdown) documents, but knit_child() should work the same way for .Rmd files: