\HeaderA{na.action}{NA Action}{na.action}
\methaliasA{na.action.default}{na.action}{na.action.default}
\keyword{NA}{na.action}
\keyword{methods}{na.action}
\begin{Description}\relax
Extract information on the NA action used to create an object.
\end{Description}
\begin{Usage}
\begin{verbatim}
na.action(object, ...)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{object}] any object whose \code{\LinkA{NA}{NA}} action is given.
\item[\code{...}] further arguments special methods could require.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
\code{na.action} is a generic function, and \code{na.action.default} its
default method.  The latter extracts the \code{"na.action"} component
of a list if present, otherwise the \code{"na.action"} attribute.

When \code{\LinkA{model.frame}{model.frame}} is called, it records any information
on \code{NA} handling in a \code{"na.action"} attribute.  Most
model-fitting functions return this as a component of their result.
\end{Details}
\begin{Value}
Information from the action which was applied to \code{object} if
\code{NA}s were handled specially, or \code{NULL}.
\end{Value}
\begin{References}\relax
Chambers, J. M. and Hastie, T. J. (1992)
\emph{Statistical Models in S.}
Wadsworth \& Brooks/Cole.
\end{References}
\begin{SeeAlso}\relax
\code{\LinkA{options}{options}("na.action")}, \code{\LinkA{na.omit}{na.omit}},
\code{\LinkA{na.fail}{na.fail}}, also for \code{na.exclude}, \code{na.pass}.
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
na.action(na.omit(c(1, NA)))
\end{ExampleCode}
\end{Examples}

