How to layout character value within R chunk

问题

In the knitr package I like the kable function. It gives a nice layout of tables and data frame like objects even as it is called from within an R code chunk. Now I want to do the same thing with a character value. Is there a function that gives a kable-like output ("kprint") that can be formated?

knitr::kable() # exists for tables
knitr::kprint() # does a function like this exists for character values?

This is what I get now:

print("character value") # within the R Chunk

Output in generated report:

## [1] "character value"

And this is what I want, just:

character value

EDIT cat("character value") is not the solution I am looking for because I don't want an R output anymore, but just a plain text.

回答1:

There are two things to do to get a "raw" character string (without any formatting or additional output like [1]) from R to TEX:

Use the chunk option results = "asis" to instruct knitr not to modify the output.
Use cat instead of print because print adds the lenght of the vector and quotes to the output.

In this context, inline output using \Sexpr{} might be useful because values in \Sexpr{} are by default printed "as they are": \Sexpr{myoutput}.

As there was the question of how to format the output in the comments, here some options:

Add LaTeX to the text you pass to cat: cat("\\emph{foo}"). Don't forget to escape \ by an additional \.
Do the same thing as above, but use a function to do the "dirty work":
```
makeItNiceR <- function(x) {
  return(paste("\\fbox{\\texttt{", x, "}}"))
}

cat(makeItNiceR("foo bar is nice"))
```
- (Note that we could use cat inside makeItNiceR to save some typing, but this makes the function less flexible and we cannot use it in combination with \Sexpr{} anymore.)

Manually add LaTeX formatting commands around \Sexpr{}:

Add formatting to \emph{\Sexpr{myoutput}} directly in LaTeX.

Combine makeItNiceR and \Sexpr{} to get nicely formatted output from \Sexpr{}:
```
\Sexpr{makeItNiceR(paste(myoutput, "is nice"))}
```

The following minimal examples demonstrates the usage of all code snippets from above:

\documentclass{article}
\begin{document}

<<results = "asis">>=
makeItNiceR <- function(x) {
  return(paste("\\fbox{\\texttt{", x, "}}"))
}

myoutput <- "slim"

cat("foo")
cat("\\emph{foo}")
cat(makeItNiceR("foo bar is nice"))
@

\paragraph{Outside of chunk:} ~\\

\Sexpr{myoutput} \\

Add formatting to \emph{\Sexpr{myoutput}} directly in LaTeX. \\

\Sexpr{makeItNiceR(paste(myoutput, "is nice"))}
\end{document}

来源：https://stackoverflow.com/questions/32327697/how-to-layout-character-value-within-r-chunk

标签

knitr