How to nest knit calls to fix duplicate chunk label errors?

Question

I'm running into a duplicate label error when I call a function that uses knit inside a knit call. If I label the chunks the problem goes away. Is there a way to call some_function in a way that doesn't collide with the parent knit call?

library(knitr)
some_function <- function(){
    knit(text ="
    ```{r }
        1
    ```
    ")
}
cat(knit(text ="
```{r }
    some_function()   
```
```{r }
    some_function()   
```
"))

Output:

```r
some_function()
```

```
## Error: duplicate label 'unnamed-chunk-1'
```

I'd have to make sure the chunk label was unique every time I called some_function. — nachocab, Jul 08 '13 at 20:29

score 3 · Accepted Answer · answered Jul 12 '13 at 07:41

3

You can use knit_child() instead of knit() in some_function():

library(knitr)
some_function <- function(){
  knit_child(text ="
    ```{r }
        1
    ```
    ")
}
cat(knit(text ="
```{r }
    some_function()   
```
```{r }
    some_function()   
```
"))

answered Jul 12 '13 at 07:41

Yihui Xie

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Thanks a lot @Yihui ! If I understood the `knit` code correctly, setting the child mode ensures that no object gets written to the `.knitEnv`, which is what was messing me up. Correct? – nachocab Jul 12 '13 at 14:42
1

`knit()` will initialize some internal objects, including the object to manage code chunks, and `knit_child()` will not; if that object is initialized again, knitr will start counting chunks from 1 again, leading to the chunks with the same label `unnamed-chunk-1` in two nested `knit()` calls and they will clash – Yihui Xie Jul 12 '13 at 19:55

score 1 · Answer 2 · answered Jul 08 '13 at 20:40

I don't understand exactly the context use of your code. Why not to use simply knitr child document feature?

Here a workaround ( hope that someone else come with a better solution specially you if you give more context)

some_function <- function(chunk.name='chunk1'){
  knit(text =sprintf("
    ```{r %s}
        1
    ```
    ",chunk.name))
}
cat(knit(text ="
```{r }
    some_function('a1')   
```
```{r }
    some_function('a2')   
```
"))

How to nest knit calls to fix duplicate chunk label errors?

2 Answers2

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