\HeaderA{p2LL}{A function to map from probes to unique Entrez Gene IDs}{p2LL}
\keyword{manip}{p2LL}
\begin{Description}\relax
For any chip, this function computes the map from  unique Entrez Gene
ID to all probes.
\end{Description}
\begin{Usage}
\begin{verbatim}
p2LL(data)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{data}] The character string naming the chip. 
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
This is essentially the computation of the reverse map, we store probe
to Entrez gene information in the \code{ENTREZID} environment. This is
used to compute the inverse mapping.
\end{Details}
\begin{Value}
A list, with length equal to the number of unique Entrez Gene IDs on
the chip, the elements correspond to the probes that map to the Gene ID.
\end{Value}
\begin{Author}\relax
R. Gentleman
\end{Author}
\begin{SeeAlso}\relax
\code{\LinkA{getLL}{getLL}}
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
 if( require("hgu95av2") ) {
 x = p2LL("hgu95av2")
 table(sapply(x, length))
}
\end{ExampleCode}
\end{Examples}