Align numeric values from knitr command \Sexpr{} by decimal in table created with booktabs and tabularx

Question

I am writing my thesis as dynamic document using .Rnw, knitr and R. I ran my statistical analyses in an external R-script, which I sourced into my main .Rnw-file.

I also want to create some tables showing summary statistics and the output from my regression analyses. For some cells I type in the value by hand and for others I call the values with the knitr command \Sexpr{} from the sourced R files.

The following MWE provides an insight into what I am talking about:

\documentclass{scrartcl}
\usepackage{tabularx}
\usepackage{booktabs}

\begin{document}

\begin{table}
\caption{This is a table}
\begin{tabularx}{\textwidth}{XXXXX}
\toprule
&\multicolumn{2}{c}{First subset} & \multicolumn{2}{c}{Second subset}\\
\cmidrule(lr){2-3} \cmidrule(lr){4-5}
& {Model1: WTP\_PR\_bin} & {Model2: WTP\_PR\_log} & {Model3: WTP\_RE\_bin} & {Model4: WTP\_RE\_log} \\ 
\midrule
Const      & \Sexpr{sprintf("%.3f", round(244/33, digits=3))}*** & 22.300  & \Sexpr{round(exp(0.987), digits=3)}  & 65.876\\
Variable 1 & \Sexpr{round(exp(0.873), digits=3)}                 &-34.445* & \Sexpr{round(sqrt(75688), digits=3)} & 0.348\\
Variable 2 & \Sexpr{78*87.343}                                   & 222.873 & -0.874                               & -1.234**\\
\bottomrule
\end{tabularx}
Note: Displayed are the coefficients; *\(p<0.1\), **\(p<0.05\), ***\(p<0.001\).
\end{table}

\end{document}

The result of the code above looks like this:

What I am aiming for right now is that the values in every column are aligned by decimal point. See the alignment of values in the table above. The values are left aligned, but not aligned to the decimal point.

Anybody any clue, how to solve that issue? I expect something like that:

Thanks for your support.

Magnus

Answer 1

Using tabular* (or tabular) rather than tabularx for numerical data:

\documentclass{scrartcl}
\usepackage{dcolumn}
\usepackage{booktabs}
\newcommand\hd[1]{\multicolumn{1}{c}{\begin{tabular}{@{}c@{}}#1\end{tabular}}}

% hack as no R on this machine
\def\Sexpr#1{12.123}
\catcode`\%=12

\begin{document}

\begin{table}
\caption{This is a table}
\begin{tabular*}{\textwidth}{@{\extracolsep{\fill}}l*{4}{D{.}{.}{4.3}}@{}}
\toprule
&\multicolumn{2}{c}{First subset} & \multicolumn{2}{c}{Second subset}\\
\cmidrule(lr){2-3} \cmidrule(lr){4-5}
& 
\hd{Model1:\\ WTP\_PR\_bin} &
\hd{Model2:\\ WTP\_PR\_log} &
\hd{Model3:\\ WTP\_RE\_bin} &
\hd{Model4:\\ WTP\_RE\_log} \\ 
\midrule
Const      & \Sexpr{sprintf("%.3f", round(244/33, digits=3))}*** & 22.300  & \Sexpr{round(exp(0.987), digits=3)}  & 65.876\\
Variable 1 & \Sexpr{round(exp(0.873), digits=3)}                 &-34.445* & \Sexpr{round(sqrt(75688), digits=3)} & 0.348\\
Variable 2 & \Sexpr{78*87.343}                                   & 222.873 & -0.874                               & -1.234**\\
\bottomrule
\end{tabular*}
Note: Displayed are the coefficients; *\(p<0.1\), **\(p<0.05\), ***\(p<0.001\).
\end{table}

\end{document}