问题
Given a list of child documents, how can you choose which to insert into a master document based on some criteria?
In my use case, I am matching the unknown entries in one dataset to the desired entries in a second dataset. The second dataset has child documents associated with each entry. If a match is found, I want to include its associated child document.
In its most basic form, this psuedo-code shows the gist of what I am trying to achieve (inspired by this question here):
```{r, eval=TRUE}
child_docs <- setNames(c(TRUE, FALSE, TRUE, FALSE),
c("doc1.Rmd", "doc2.Rmd","doc3.Rmd","doc4.Rmd"))
for(i in seq_along(child_docs)){
file <- names(child_docs)[i]
eval_status <- child_docs[i]
```{r child = file, eval = eval_status}
```
}
```
Or, more simply:
```{r}
child_docs <- c("child/doc1.Rmd", "child/doc2.Rmd","child/doc3.Rmd","child/doc4.Rmd")
```
```{r child = child_docs}
```
I have also tried these, but they did not work (RMarkdown code chunk):
```{r}
child_docs <- c("child/doc1.Rmd", "child/doc2.Rmd","child/doc3.Rmd","child/doc4.Rmd")
for(i in seq_along(child_docs)){
doc <- child_docs[i]
knit_child(doc)
}
```
(Directly within the RMarkdown document):
`for(i in seq_along(child_doc)){ doc <- child_doc[i]; knit_child(doc)}`
For reference, the manual for doing this (in LaTeX) is here.
回答1:
Found the solution myself; simply pass a vector of child documents to the code chunk.
```{r}
child_docs <- c("doc1.Rmd", "doc2.Rmd","doc3.Rmd","doc4.Rmd")
```
```{r, child = child_docs}
```
After implementing my own code in order to obtain the list of child docs to include.
回答2:
You can dynamically render a child document
```{r, result='asis'}
cat(knitr::knit_child("child.Rmd", quiet=TRUE))
```
which gives you great flexibility.
The "trick" is the result='asis' so that the output is then passed on for conversion (as opposed to "knitting").
Alternatively, you can tag the object and avoid the "asis" in the chunk options:
```{r}
cat(knitr::asis_output(knitr::knit_child("child.Rmd", quiet=TRUE)))
```
This is more robust, as it allows you to use this in nested functions, etc., and not have to rely on the caller having set the "correct" chunk options.
If you want to pass in "current" variables and libraries, pass in the current environment too:
```{r, result='asis'}
cat(knitr::knit_child("child.Rmd", quiet=TRUE, envir=environment()))
```
来源：https://stackoverflow.com/questions/39377465/conditionally-include-a-list-of-child-documents-in-rmarkdown-with-knitr