[Tex/LaTex] How to modify knitr output chunk

knitrr

I know that it's possible to tweak the output of a knitr code chunk so that it
looks the way you want. My problem occurs when using the parskip package.
The parskip package adds an extra bit of space below the code output, which doesn't
look great. Here's a minimal .Rnw file.

\documentclass[11pt]{article}
\usepackage[utf8]{inputenc}
\usepackage[margin=1in]{geometry}
\usepackage{parskip}

\begin{document}
\setlength{\parindent}{0in}
Some text above chunk
<<echo=TRUE>>=
2 + 2
@
Some text below. The space above this is too big when using the \texttt{parskip} package.
Some text below. The space above this is too big when using the \texttt{parskip} package.
Some text below. The space above this is too big when using the \texttt{parskip} package.

A nice space between paragraphs.
\end{document}

Best Answer

This not an elegant answer but you can 'fix' the excess space with the inclusion of negative vertical space. See the modified code.

\documentclass[11pt]{article}
\usepackage[utf8]{inputenc}
\usepackage[margin=1in]{geometry}
%\usepackage{parskip}

\begin{document}
\setlength{\parindent}{0in}
Some text above chunk
<<echo=TRUE>>=
2 + 2
@
\vspace{-1em}  %%% this moves the following text up the height of an 'm'
Some text below. The space above this is too big when using the \texttt{parskip} package.
Some text below. The space above this is too big when using the \texttt{parskip} package.
Some text below. The space above this is too big when using the \texttt{parskip} package.

A nice space between paragraphs.
\end{document}

Option 1: Using `knit_child()` with inline R code

Say your setup is like the following. In the same directory, you have:

`graph.R`

## ---- graph
library(ggplot2)
CarPlot <- ggplot() +
    stat_summary(data= mtcars,
                 aes(x = factor(gear),
                     y = mpg
                 ),
                 fun.y = "mean",
                 geom = "bar"
                 )
CarPlot

`chapter1.Rnw`

Hey, look, a graph (Figure~\ref{fig:graph})!

<<graph, echo=FALSE, message=FALSE, fig.lp='fig:', out.width='.5\\linewidth', fig.align='center', fig.cap="A graph", fig.pos='h!'>>=
@

`main.Rnw`

\documentclass{article}

\begin{document}

<<external-code, echo=FALSE, cache=FALSE>>=
read_chunk('./graph.R')
@

\Sexpr{knit_child('chapter1.Rnw')}

\end{document}

Then, you can knit the main.Rnw file and compile the resulting .tex file with either pdflatex or xelatex.

The output is:

enter image description here

Note that you can also read the external .R file from the child .Rnw file.

So, the following would have worked just as well.

`chapter1-mod.Rnw`

<<external-code, echo=FALSE, cache=FALSE>>=
read_chunk('./graph.R')
@

Hey, look, a graph (Figure~\ref{fig:graph})!

<<graph, echo=FALSE, message=FALSE, fig.lp='fig:', out.width='.5\\linewidth', fig.align='center', fig.cap="A graph", fig.pos='h!'>>=
@

`main-mod.Rnw`

\documentclass{article}

\begin{document}

\Sexpr{knit_child('chapter1-mod.Rnw')}

\end{document}

Option 2: Using chunk option `child`

Assuming you have graph.R and chapter1.Rnw from above in the same directory, then your main.Rnw should be:

\documentclass{article}

\begin{document}

<<external-code, echo=FALSE, cache=FALSE>>=
read_chunk('./graph.R')
@

<<child-demo, child='chapter1.Rnw'>>=
@

\end{document}

Note that you can also read the external .R file from within the child document in this case, too.

So, assuming you had graph.R and chapter1-mod.Rnw from above in the same directory, then your main-mod.Rnw file should be:

\documentclass{article}

\begin{document}

<<child-demo, child='chapter1-mod.Rnw'>>=
@

\end{document}

Best Answer

Related Solutions

[Tex/LaTex] tikzDevice is not getting sizes right (knitr)

[Tex/LaTex] Building TeX file from knitr Rnw as child of larger parent TeX file to use R objects and output

Option 1: Using knit_child() with inline R code

graph.R

chapter1.Rnw

main.Rnw

chapter1-mod.Rnw

main-mod.Rnw

Option 2: Using chunk option child

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