knitr：章节名称是R块代码的名称

Question

I want to use the R chunk code output as the Chapter Name but could not figured out how to do this. Below is my minimum working example.

\documentclass{book}
\usepackage[T1]{fontenc}

\begin{document}

\chapter{cat(
<< label=Test1, echo=FALSE, results="asis">>=
2+1
@
)
}

Chapter name is the output of R chunk Code.

\end{document}

Answer 1

This works for me

<< label=Test1, echo=FALSE>>=
cn <- 2+1
@

\chapter*{Chapter \Sexpr{cn}}

Answer 2

在RMarkdown中，您可以使用以下代码

# `r I(1+2)`