\begin{Schunk}
\begin{Sinput}
 dat$wn <- paste(dat$w, dat$rn, sep = "_")
 head(dat[ ,c("w", "rn", "wn")])
\end{Sinput}
\begin{Soutput}
  w rn  wn
1 g  1 g_1
2 f  2 f_2
3 i  3 i_3
4 h  4 h_4
5 g  5 g_5
6 i  6 i_6
\end{Soutput}
\end{Schunk}
