\HeaderA{rmono}{Randomly Impose a Monotone Missingness Pattern}{rmono}
\keyword{datagen}{rmono}
\begin{Description}\relax
Randomly impose a monotone missingness pattern by replacing the ends
of each column of the input matrix by a random number of \code{NA}s
\end{Description}
\begin{Usage}
\begin{verbatim}
rmono(x, m = 7, ab = NULL)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{x}] data \code{matrix} 
\item[\code{m}] minimum number of non-\code{NA} entries in each column 
\item[\code{ab}] a two-vector of \eqn{\alpha}{} (\code{ab[1]}) and
\eqn{\beta}{} (\code{ab[2]}) parameters to a
Beta\eqn{(\alpha, \beta)}{} distribution
describing the proportion of \code{NA} entries in each column.
The default setting \code{ab = NULL} yields a uniform distribution 
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
The returned \code{x} always has one (randomly selected)
complete column, and no column has fewer than \code{m}
non-missing entries.  Otherwise, the proportion of missing entries
in each column can be uniform, or it can have a beta
distribution with parameters \eqn{\alpha}{} (\code{ab[1]}) and
\eqn{\beta}{} (\code{ab[2]})
\end{Details}
\begin{Value}
returns a \code{matrix} with the same dimensions as the input \code{x}
\end{Value}
\begin{Author}\relax
Robert B. Gramacy \email{bobby@statslab.cam.ac.uk}
\end{Author}
\begin{References}\relax
\url{http://www.statslab.cam.ac.uk/~bobby/monomvn.html}
\end{References}
\begin{SeeAlso}\relax
\code{randmvn}
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
out <- randmvn(10, 3)
rmono(out$x)
\end{ExampleCode}
\end{Examples}

