How to more easily reuse many chunks?

Question

I want to reuse code chunks. It works when I do the following:

# Reusing Code Chunks {.tabset .tabset-pills}

```{r, ref.label='a-chunk-not-in-my-example-1'}
```

## 1st model

```{r, ref.label='a-chunk-not-in-my-example-2'}
```

## 2nd model 

``` {r, ref.label='a-chunk-not-in-my-example-3'}
```

Because I have 100 chunks, this approach is cumbersome.

I have tried using a loop with child documents and knitr::knit_child(), but I have not been able to print the results or a header. I am also aware of knitr::asis_output(), but it does not appear to work in a loop.

Answer 1

If I understand correctly, here is a full example of how you could programmatically reference previous chunks by creating a series of child.Rmd documents and applying knitr::knit_child().

Basically we cat() all of the desired output from a single chunk with option results='asis'.

---
title: "Programmatically Referencing Chunks"
output: html_document
date: "2025-02-14"
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE)
```

# Original Chunks {.tabset .tabset-pills}

## Chunk 1

```{r chunk-1}
"Chunk 1 contents"
```

## Chunk 2

```{r chunk-2}
summary(cars)
```

## Chunk 3

```{r chunk-3}
plot(pressure)
```

# Referenced Chunks {.tabset .tabset-pills}

```{r, echo=FALSE, results='asis'}
# create vector of chunk labels to iterate over
all_chunk_labels <- knitr::all_labels()
desired_chunk_labels <- all_chunk_labels[grepl("^chunk", all_chunk_labels)]

for(chunk_label in desired_chunk_labels) {
  # output markdown for header
  cat(paste("## Chunk", sub("chunk-", "", chunk_label)))

  # construct child.Rmd using ref.label chunk option
  c(
    sprintf('```{r, ref.label="%s"}', chunk_label),
    '```'
  ) |>
    writeLines("child.Rmd")
  
  # knit child and output results
  res <- knitr::knit_child('child.Rmd', quiet = TRUE)
  cat(res, sep = '\n')
  
  # clean up
  unlink("child.Rmd")
}
```

_{Reprex files hosted with on GitHub}