lstdefinestyle{Routstyle}{%
  fancyvrb=false,
  literate={~}{{$sim$}}1{R^2}{{$R^{2}$}}2{^}{{$^{scriptstylewedge}$}}1{R-squared}{{$R^{2}$}}2,%
  frame=single,
  framerule=0.2pt,
  framesep=1pt,
  basicstyle=RoutcolorRoutsizettfamily,%
  backgroundcolor=Routbackground}

lstdefinestyle{Routstyle}{%
  language=R,%
  basicstyle={RoutcolorSweavesizettfamily},
  backgroundcolor=Routbackground,%
}

documentclass{tufte-book}

usepackage{Sweavel}

usepackage{amsthm}
usepackage{mathtools}
usepackage{soul}

%%%%%%%%%%
% R example
%%%%%%%%%%
newtheoremstyle{rex}{}{}{}{.45textwidth}{}{}{1 mm}{}
theoremstyle{rex}
newtheorem{rexample}{R example}[chapter]

%%%%%%%%%%
% boxes
%%%%%%%%%%
usepackage[framemethod=TikZ]{mdframed}
mdfdefinestyle{style2}{
    backgroundcolor=gray!10,
}
usepackage[strict]{changepage}
%%%%%%%%%%

%%%%%%%%%%
% crossref
%%%%%%%%%%
usepackage[capitalize,noabbrev]{cleveref}
    crefname{rexample}{Example}{Examples}%
%%%%%%%%%%

%%%%%%%%%%
% layout
%%%%%%%%%%
newcommand{blankpage}{newpagehbox{}thispagestyle{empty}newpage}
%%%%%%%%%%


%%%%%%%%%%
% listings
%%%%%%%%%%
newcommand{indexfunction}[1]{index{#1@texttt{#1}}}
usepackage{listings}
lstset{language = R,
  frame = single,
}
defRcolor{color{black}}
defRoutcolor{color{black}}
defRcommentcolor{color{red}}
defRbackground{color[rgb]{0.992, 0.965, 0.894}}
defRoutbackground{color[rgb]{0.894, 0.965, 0.992}}
definecolor{lightYellow}{rgb}{0.992, 0.965, 0.894}
sethlcolor{lightYellow}
%%%%%%%%%%

lstdefinestyle{Routstyle}{% <==========================================
  language=R,%
  basicstyle={RoutcolorSweavesizettfamily},
  backgroundcolor=Routbackground,%
} % <===================================================================
%%%%%%%%%%
% book metadata
%%%%%%%%%%
title[]{}
author[]{}
publisher{}
%%%%%%%%%%


begin{document}

begin{Schunk}
begin{rexample}
label{set1}hfill{}
begin{Sinput}
setS <- letters[1:5] %>% print()
end{Sinput}
begin{Soutput}
[1] "a" "b" "c" "d" "e"
end{Soutput}
end{rexample}
end{Schunk}

begin{Schunk}
begin{rexample}
label{set2}hfill{}
begin{Sinput}
"e" %in% setS
end{Sinput}
begin{Soutput}
[1] TRUE
end{Soutput}
begin{Sinput}
"f" %in% setS
end{Sinput}
begin{Soutput}
[1] FALSE
end{Soutput}
end{rexample}
end{Schunk}

end{document}