\HeaderA{causton}{Yeast mRNA Expression Data}{causton}
\keyword{datasets}{causton}
\begin{Description}\relax
This data set contains mRNA expression from a microarray experiment involving yeast grown under a variety of altered environments (e.g. acid, heat, sorbitol, etc.)
\end{Description}
\begin{Usage}
\begin{verbatim}data(causton)\end{verbatim}
\end{Usage}
\begin{Format}\relax
A matrix whose rows are the 6015 genes and whose columns are the 45 experimental conditions.
\end{Format}
\begin{Source}\relax
\url{http://web.wi.mit.edu/young/environment}
\end{Source}
\begin{References}\relax
Causton, H. C. et al. 2001 ``Remodeling of Yeast Genome Expression in Response to Environmental Changes.'' Molecular Biology of the Cell \bold{12}, 323--337.
\end{References}
\begin{Examples}
\begin{ExampleCode}
data(causton)

## Find the 3000 most variable genes, according to sd/mean:

varMeas<-function(vec) sd(vec)/mean(vec)
variability<-apply(causton,1,varMeas)

rks<-rank(variability)

causton3000<-causton[rks>length(rownames(causton))-3000,]
\end{ExampleCode}
\end{Examples}

