Knitr Extensions
knit_ex is a utility function for running small knitr examples,
e.g., to illustrate functionalities or issues.
hook_backspace is a chunk hook that enables the use of backspace
characters in the output (e.g., as used in progress bars), and still
obtain a final output as in the console.
knit_ex(x, ..., quiet = TRUE, open = FALSE) hook_try(before, options, envir) hook_backspace() hook_toggle()
x |
text to knit as a character vector |
... |
|
quiet |
logical that indicates if knitting should be quiet (no progress bars etc..). |
open |
logical, only used when |
before |
logical that indicates when the hook is being called: before or after the chunk is processed. |
options |
list of current knitr chunk options |
envir |
environment where the chunk is evaluated |
knit_ex returns the generated code, although invisibly when open=TRUE.
hook_try: is a knitr hook to enable showing error
messages thrown by try.
The function is not meant to be called directly, but only registered
using knitr::knit_hooks (see details on this dedicated man page).
This simply defines a function try in envir that prints
the error message if any, and is called instead of base try.
hook_toggle: is a chunk hook that adds clickable elements to toggle indvidual
code chunks in HTML documents generated from .Rmd files.
library(knitr)
knit_ex("1 + 1")
library(knitr)
# standard error message is caught
knit_ex("stop('ah ah')")
# with try the error is output on stderr but not caughted by knitr
knit_ex("try( stop('ah ah') )")
# no message caught
knit_ex("
^^^{r, include = FALSE}
knit_hooks$set(try = pkgmaker::hook_try)
^^^
^^^{r, try=TRUE}
try( stop('ah ah') )
^^^")
# Correctly formatting backspaces in chunk outputs
tmp <- tempfile(fileext = '.Rmd')
cat(file = tmp, "
^^^{r, include = FALSE}
library(knitr)
knit_hooks$set(backspace = pkgmaker::hook_backspace())
^^^
Default knitr does not handle backspace and adds a special character:
^^^{r}
cat('abc\bd')
^^^
Using the hook backspace solves the issue:
^^^{r, backspace=TRUE}
cat('abc\bd')
^^^
")
# knit
out <- knitr::knit2html(tmp, fragment.only = TRUE)
# look at output
## Not run:
browseURL(out)
edit( file = out)
## End(Not run)
# cleanup
out_files <- list.files(dirname(out), full.names = TRUE,
pattern = paste0("^", tools::file_path_sans_ext(out)))
unlink(c(tmp, out_files))
knit_ex("
Declare chunk hook:
^^^{r, setup}
library(knitr)
knit_hooks$set(toggle = hook_toggle())
^^^
The R code of this chunk can be toggled on/off, and starts visible:
^^^{r, toggle=TRUE}
print(1:10)
^^^
The R code of this chunk can be toggled on/off, and starts hidden:
^^^{r, toggle=FALSE}
print(1:10)
^^^
This is a plain chunk that cannot be toggled on/off:
^^^{r}
print(1:10)
^^^
Now all chunks can be toggled and start visible:
^^^{r, toggle_all}
opts_chunk$set(toggle = TRUE)
^^^
^^^{r}
sample(5)
^^^
To diable the toggle link, one can pass anything except TRUE/FALSE:
^^^{r, toggle = NA}
sample(5)
^^^
", open = TRUE)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.