\begin{Schunk}
\begin{Sinput}
 colMresults3 <- vapply(jumboData, colMeans, numeric(3))
 ## 3rd argument gives structure required in output from colMeans
 str(colMresults3)
\end{Sinput}
\begin{Soutput}
 num [1:3, 1:150] 1 90.9 30.9 2 90 ...
 - attr(*, "dimnames")=List of 2
  ..$ : chr [1:3] "ds" "x1" "x2"
  ..$ : NULL
\end{Soutput}
\end{Schunk}
