\HeaderA{ygs98MAPCOUNTS}{Number of mapped keys for the maps in package ygs98.db}{ygs98MAPCOUNTS}
\keyword{datasets}{ygs98MAPCOUNTS}
\begin{Description}\relax
ygs98MAPCOUNTS provides the "map count" (i.e. the count of mapped
keys) for each map in package ygs98.db.
\end{Description}
\begin{Details}\relax
This "map count" information is precalculated and stored in the package
annotation DB. This allows some quality control and is used by the
\code{\LinkA{checkMAPCOUNTS}{checkMAPCOUNTS}} function defined in
AnnotationDbi to compare and validate different methods (like
\code{count.mappedkeys(x)} or \code{sum(!is.na(as.list(x)))})
for getting the "map count" of a given map.
\end{Details}
\begin{SeeAlso}\relax
\code{\LinkA{mappedkeys}{mappedkeys}},
\code{\LinkA{count.mappedkeys}{count.mappedkeys}},
\code{\LinkA{checkMAPCOUNTS}{checkMAPCOUNTS}}
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
  ygs98MAPCOUNTS
  mapnames <- names(ygs98MAPCOUNTS)
  ygs98MAPCOUNTS[mapnames[1]]
  x <- get(mapnames[1])
  sum(!is.na(as.list(x)))
  count.mappedkeys(x)   # much faster!

  ## Check the "map count" of all the maps in package ygs98.db
  checkMAPCOUNTS("ygs98.db")
\end{ExampleCode}
\end{Examples}

