I'm in the midst of writing a textbook. I frequently use custom code blocks to explain technical concepts. These are quite nice, but sometimes I want to embed an r chunk within a custom code block. As an example, I would like to do the following:
```{block, type="rmdnote"}
This is a very tricky concept to master. Let's look at a plot and output generated from R:
```{r, echo=FALSE}
plot(1:10, 1:10)
summary(1:10)
```
```
This will not work. Is there any way to embed an r chunk within a custom chunk?
Related
I'm having a problem with assigning LaTeX environments within an RMarkdown for-loop code-chunk.
In short, I've written an R Markdown document and a series of R-scripts to automatically generate PDF reports at the end of a long data analysis pipeline. The main section of the report can have a variable number of sections that I'm generating using a for-loop, with each section containing a \subsection heading, a datatable and plot generated by ggplot. Some of these sections will be very long (spanning several pages) and some will be very short (~1/4 of a page).
At the moment I'm just inserting a \pagebreak at the end of each for-loop iteration, but that leaves a lot of wasted space with the shorter sections, so I'm trying to "group" each section (i.e. the heading, table and chart) so that there can be several per page, but they will break to a new page if the whole section won't fit.
I've tried using a figure or minipage environment, but for some reason those commands are printed as literal text when the plot is included; these work as expected with the heading and data table, but aren't returned properly in the presence of the image.
I've also tried to create a LaTeX samepage environment around the whole subsection (although not sure this will behave correctly with multi-page sections?) and then it appears that the Markdown generated for the plot is not interpreted correctly somewhere along the way (Pandoc?) when it's within that environment and throws an error when compiling the TeX due to the raw Markdown ![]... image tag.
Finally, I've also tried implementing \pagebreak[x] and \nopagebreak[y] hints at various points in the subsection but can't seem get these to be produce the desired page breaking behaviour.
I've generated an MWE that reproduces my issues below.
I'd be really grateful for any suggestions on how to get around this, or better ways of approaching "grouping" of elements that are generated in a dynamic fashion like this?
---
title: "Untitled"
author: "I don't know what I'm doing"
date: "26/07/2020"
output:
pdf_document:
latex_engine: xelatex
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE, dev = "cairo_pdf")
```
```{r cars, results='asis'}
for (i in 1:5){
cat("\\begin{figure}")
cat(paste0("\\subsection{This is subsection ",i,"}"))
cat("\\Huge Here's some bulk text that would represent a data table... kasvfkwsvg fiauwe grfiwgiu iudaldbau iausbd ouasbou asdbva asdbaisd i iuahihai hiuh iaiuhqijdblab ihlibljkb liuglugu h uhi uhi uhqw iuh qoijhoijoijoi qwegru wqe grouw egq\\newline")
plot(mtcars$wt,mtcars[,i])
cat("\\end{figure}")
}
```
Edit to add: interestingly these figure and minipage environments seems to work as expected when executing the same example in an .Rnw using knitr... so does that narrow it down to an issue with Pandoc? Again, any help much appreciated!
What happens is that the raw TeX commands are not treated as TeX when going through Markdown. You can fix that by explicitly marking the relevant snippets as LaTeX:
for (i in 1:5){
cat("`\\begin{figure}`{=latex}")
cat(paste0("\\subsection{This is subsection ",i,"}"))
cat("\\Huge Here's some bulk text that would represent a data table... kasvfkwsvg fiauwe grfiwgiu iudaldbau iausbd ouasbou asdbva asdbaisd i iuahihai hiuh iaiuhqijdblab ihlibljkb liuglugu h uhi uhi uhqw iuh qoijhoijoijoi qwegru wqe grouw egq\\newline")
plot(mtcars$wt,mtcars[,i])
cat("`\\end{figure}`{=latex}")
}
See the generic raw attribute section in the pandoc manual for details.
In bookdown how can I include R code within a custom block, whereby the R code will be parsed. Like in the example below the r code (plot function) will not be parsed. Is there a way to make this work?
```{block2 type='test'}
some text here
plot(1:10)
```
You can use text references as a hack. This seems to work as long as valid_markdown contains a single paragraph/line of markdown.
```{r}
valid_markdown <- your_function()
```
(ref:my_hack) `r valid_markdown`
```{block2, type="block"}
(ref:my_hack)
```
This hack works fine with text. Getting it work with plots will require a bit more work.
I'm creating a tutorial that involves telling the reader what to put into a file we'll call utils.R. The user would get the tutorial as an HTML file. Throughout the tutorial utils.R changes and the Rmd document uses the code in utils.R as it exists at that stage of the tutorial. During the rendering, I'd like for the code chunks to use source("utils.R") as it exists at that stage of the tutorial. I'm looking for a way to either...
1. Write the contents of a code chunk to a file. For example...
```{r utils_1}
summary(cars)
median(cars$speed)
```
Is there a way to write the code in utils_1 to a file?
2. Create a nicely formatted code chunk from a text string (I know how to write that to a file). For example...
z <- "summary(cars)\nmedian(cars$speed)"
write(z, "utils.R")
Will generate utils.R, but is there a way to turn z into a properly formatted code chunk.
I could create multiple versions of utils.R and use echo=F to hide that I'm loading that behind the scenes, but that seems like a pain.
Not sure if this is what are you looking for but you can use child option to generate them from another file. I use it for automated reports as it helps to keep the main Rmd a bit simpler
```{r child=utils.R}
```
I often place the child code in the YAML though, and call it (matter of tastes I guess...):
---
params:
utils: "utils.R"
---
```{r child=params$utils}
```
I'm writing a report in R Markdown in which I don't want to print any of my R code in the main body of the report – I just want to show plots, calculate variables that I substitute into the text inline, and sometimes show a small amount of raw R output. Therefore, I write something like this:
In the following plot, we see that blah blah blah:
```{r snippetName, echo=F}
plot(df$x, df$y)
```
Now...
That's all well and good. But I would also like to provide the R code at the end of the document for anybody curious to see how it was produced. Right now I have to manually write something like this:
Here is snippet 1, and a description of what section of the report
this belongs to and how it's used:
```{r snippetName, eval=F}
```
Here is snippet 2:
```{r snippetTwoName, eval=F}
```
<!-- and so on for 20+ snippets -->
This gets rather tedious and error-prone once there are more than a few code snippets. Is there any way I could loop over the snippets and print them out automatically? I'm hoping I could do something like:
```{r snippetName, echo=F, comment="This is snippet 1:"}
# the code for this snippet
```
and somehow substitute the following result into the document at a specified point when it's knitted:
This is snippet 1:
```{r snippetName, eval=F}
```
I suppose I could write some post-processing code to scan through the .Rmd file, find all the snippets, and pull out the code with a regex or something (I seem to remember there's some kind of options file you can use to inject commands into the pandoc process?), but I'm hoping there might be something simpler.
Edit: This is definitely not a duplicate – if you read my question thoroughly, the last code block shows me doing exactly what the answer to the linked question suggests (with a slight difference in syntax, which could have been the source of the confusion?). I'm looking for a way to not have to write out that last code block manually for all 20+ snippets in the document.
This is do-able within knitr, no need to use pandoc. Based on an example posted by Yihui at https://github.com/yihui/knitr-examples/blob/master/073-code-appendix.Rnw
Set echo=FALSE throughout your document: opts_chunk$set(echo = FALSE)
Then put this chunk at the end to print all code:
```{r show-code, ref.label=all_labels(), echo = TRUE, eval=FALSE}
```
This will print code for all chunks. Currently they all show up in a single block; I'd love to figure out how to put in the chunk label or some other header... For now I start my chunks with comments (probably not a bad idea in any case).
Updated: to show only the chunks that were evaluated, use:
ref.label = all_labels(!exists('engine')) - see question 40919201
Since this is quite difficult if not impossible to do with knitr, we can take advantage of the next step, the pandoc compilation, and of pandoc's ability to manipulate content with filters. So we write a normal Rmd document with echo=TRUE and the code chunks are printed as usual when they are called.
Then, we write a filter that finds every codeblock of language R (this is how a code chunk will be coded in pandoc), removes it from the document (replacing it, here, with an empty paragraph) and storing it in a list. We then add the list of all codeblocks at the end of the document. For this last step, the problem is that there really is no way to tell a python filter to add content at the end of a document (there might be a way in haskell, but I don't know it). So we need to add a placeholder at the end of the Rmd document to tell the filter to add the R code at this point. Here, I consider that the placeholder will be a CodeBlock with code lastchunk.
Here is the filter, which we could save as postpone_chunks.py.
#!/usr/bin/env python
from pandocfilters import toJSONFilter, Str, Para, CodeBlock
chunks = []
def postpone_chunks(key, value, format, meta):
if key == 'CodeBlock':
[[ident, classes, keyvals], code] = value
if "r" in classes:
chunks.append(CodeBlock([ident, classes, keyvals], code))
return Para([Str("")])
elif code == 'lastchunk':
return chunks
if __name__ == "__main__":
toJSONFilter(postpone_chunks)
Now, we can ask knitr to execute it with pandoc_args. Note that we need to remember to add the placeholder at the end of the document.
---
title: A test
output:
html_document:
pandoc_args: ["--filter", "postpone_chunks.py"]
---
Here is a plot.
```{r}
plot(iris)
```
Here is a table.
```{r}
table(iris$Species)
```
And here are the code chunks used to make them:
lastchunk
There is probably a better way to write this in haskell, where you won't need the placeholder. One could also customize the way the code chunks are returned at the end to add a title before each one for instance.
In R, using knitr, is there a way to prevent line breaks in the HTML when results='hide' and echo=FALSE?
In this case:
First I do this,
```{r results='hide', echo=FALSE}
x=4;x
```
then I do that.
I get:
First I do this,
then I do that.
with both a break and an extra line between.
I'd like to get:
First I do this, then I do that.
instead.
Generally speaking, I'd like for code chunks to not insert new lines so that markdown is free to eat the one after the first line of text.
Thanks,
I assume you're creating an HTML document from an R Markdown document. In that case, you can use the inline R code capability offered by knitr by using the ` characters starting with the letter r.
Example:
In your R Markdown, write:
First I do this,`r x=4` then I do that. I can call x by doing `r x`.
And as output, you get:
First I do this, then I do that. I can call x by doing 4.
Note that in my example, I evaluated the variable x, but if you do not want to evaluate it, you do not have to. The variable x should still be assigned a value of 4 from the
`r x=4`
part of the R Markdown.
This is Inline R Code, and is documented here under the section "Inline R Code".
EDIT:
Note that Inline R Code has properties that are analogous to "echo=FALSE". And if you want to hide the results from inline R code, you can use base R functions to hide the output. See this question.
Try something like:
``` {r , results="asis", echo=F, eval=T}
if(showMe){
cat("printed")
} else {
cat("<!-- no break line -->")
}
```