Selecting code chunk in Rmarkdown

Question

I am writing an RMarkdown file, which is a document that is a hybrid of text and R code. Here is an example of what that document could look like:

Here is an example of text within my Rmarkdown file. 
This is used to describe the code block below:

```{r}
dataframe <- outcome.df %>%
  na.omit() %>%
  group_by(Hospital, State) %>%
  arrange(desc(HeartAttackDeath)) %>%
```

Here is an example of another text block
And the following is an example of another code chunk:

```{r}
result <- lapply(names(dataframe), complete.cases)
```

I would like to move all of the code to another document. How would I go about selecting just the code, using vim? i.e. everything between ```{r} and ```

Answer 1

This seems like a prime case for a text object, but unfortunately, Vim doesn't recognize ```{R} or ``` as text object delimiters.

There's at least three options that do work:

1. Click and drag with the mouse. A bit blasphemous, perhaps, but it can get the job done if there's not too much needing to be selected and your Vim or equivalent was built with mouse support.

---

2. Position your cursor on the first line of what you want selected, press Shift + v, then use gg or j to jump down to the last line you want selected. Having visible line numbers can be helpful here. Absolute line numbers for the count for gg, relative line numbers for the count for j.

---

3. This requires a little set up, but doesn't require you to think about how many lines you're selecting, and makes repeated use almost trivial.

:let @/ = "```"
:let @a = gnVnkoj

This can then be used by positioning the cursor above the section you want to select (even above the delimiter, but after any preceding sections' delimiters), then just running @a.

Explanation:

The first line, simply sets the "last used" search pattern without actually jumping to it by directly setting the search register. The second line sets up a macro in the a register. gn jumps to the next item of the last used search pattern (should the the opening delimiter) and enters visual mode, selecting it. Shift+v switches to line-wise visual mode. n jumps to the next found instance of the search pattern (should be the closing delimiter). k moves up a line to deselect the delimiter. o moves the cursor to the other end of the selection and "reverses" the selection, so it starts at the bottom and ends at the top, where the cursor now is. j moves down a line to deselect the opening delimiter.

Answer 2

You can try this:

ggqrq

and then

:execute '/\%>' . line('.') . 'l^```{r}' | +1,/^```$/-1y R | normal @:

What it does:

gg goes to first position in the buffer;

qrq starts to record a macro on register r and ends it immediately; it simply clears the register r;

:execute '/\%>' . line('.') . 'l^```{r}' searches for a line after current one (see :help /\%>l) with the pattern ^```{r};

| separates this command from the next;

+1,/^```$/-1y R yanks to register R from the next line till the next one that starts with ^```$ less one; as we used capital R, the new content is appended to what was already there;

| separates this command from the next;

normal @: re-executes last : command (this whole line).

At the end you will have all the content you want in the r register.

Answer 3

if of vim-textobj-markdown

When you use vim and do not mind to use a plugin, you can always check

https://github.com/kana/vim-textobj-user/wiki

In your case you will find the plugin https://github.com/coachshea/vim-textobj-markdown

This plugin maps by default if to address the inner of a code block.

There are more plugins which you could consider, e.g.

• vim-sandwich provides interactive text objects by querying the beginning and end specifier:
  is <Plug>(textobj-sandwich-query-i).

Also creating your own textobject would be an option:

• https://vim.fandom.com/wiki/Creating_new_text_objects

If you get fancy, you could write a plugin based on targets.vim similar to line-targets.vim to get a very comprehensive experience of textobjects, something like

 if  af  If  Af
inf anf Inf Anf
ilf alf Ilf Alf

There is a pending PR for vimtex (a LaTeX plugin) to define textobjects for LaTeX commands and environments based on targets.vim: see the cheatsheet for a quick look.

However, I doubt that any of this will help you in RStudio.