Beamer 中带有 knitr 的 R 函数的参数

Question

我正在使用helpExtract.R函数（可以从这里)使用R来获取函数的参数。我的 ( ) MWE 是Beamerknitr.Rnw

\documentclass{beamer}

\usepackage{ragged2e}   %new code
\usetheme{default}

\addtobeamertemplate{block begin}{}{\justifying}  %new code
\addtobeamertemplate{knitrout begin}{}{\justifying}  %new code
\addtobeamertemplate{alltt begin}{}{\justifying}  %new code




<< label = setup, include = FALSE>>=
opts_chunk$set(size = 'footnotesize')
options(replace.assign = TRUE, width = 60)
@


\begin{document}


\begin{frame}[fragile]{Linear Model}

\begin{block}{lm}

<< label=lm-args, echo=FALSE, comment=NA>>=
str(args(lm))
@ 
\end{block}

\end{frame}



\begin{frame}[fragile]{Linear Model}

\begin{block}{lm function with testHelpExtract}

<< label = helpExtract-fn, echo = FALSE >>=
library(devtools)
source("helpExtract.R")
@


\Sexpr{knit_child(textConnection(helpExtract(lm, section="Usage", type = "s_code")), options = list(tidy = TRUE, echo=TRUE, eval = FALSE))}


\end{block}

\end{frame}



\begin{frame}[fragile]{Linear Model}

\begin{block}{lm function with testHelpExtract}

\Sexpr{knit_child(textConnection(helpExtract(lm, section="Arguments", type = "s_code")[1:15]), options = list(tidy = FALSE, echo=TRUE, eval = FALSE))}


\end{block}

\end{frame}


\begin{frame}[fragile]{Linear Model}

\begin{block}{lm function with testHelpExtract}

\Sexpr{knit_child(textConnection(helpExtract(lm, section="Arguments", type = "s_code")[16:25]), options = list(tidy = FALSE, echo=TRUE, eval = FALSE))}


\end{block}

\end{frame}

\end{document}

我对这个 MWE 有几个疑问。

问题

1. 无法对齐块中的文本。

2. 即使收到输出，仍收到此错误消息：错误消息

   解析错误（文本 = 代码）：：1:14：意外符号 1：公式：对象 ^

任何帮助解决这些问题的帮助都将不胜感激。谢谢