\Header{rock-MASS}{Measurements on Petroleum Rock Samples}
\alias{rock}{rock-MASS}
\keyword{datasets}{rock-MASS}
\begin{Description}\relax
Twelve core samples from petroleum reservoirs were sampled by 4
cross-sections.  Each core sample was measured for permeability, and
each cross-section has total area of pores, total perimeter of pores,
and shape.
\end{Description}
\begin{Usage}
\begin{verbatim}
data(rock)
\end{verbatim}
\end{Usage}
\begin{Format}\relax
A data frame with 48 rows and 4 numeric columns.
\Tabular{ll}{
\code{area}  & area of pores space, in pixels
out of 256 by 256 \\
\code{peri}  & perimeter in pixels \\
\code{shape} & perimeter/sqrt(area) \\
\code{perm}  & permeability in milli-Darcies
}
\end{Format}
\begin{Source}\relax
Data from BP Research, image analysis by Ronit Katz, U. Oxford.

Katz, R. (1995) \emph{Spatial Analysis of Pore Images}. D.Phil. thesis,
Department of Statistics, University of Oxford.
\end{Source}
\begin{References}\relax
Venables, W. N. and Ripley, B. D. (2002)
\emph{Modern Applied Statistics with S.} Fourth edition.  Springer.
\end{References}

