\HeaderA{mean}{Arithmetic Mean}{mean}
\methaliasA{mean.data.frame}{mean}{mean.data.frame}
\methaliasA{mean.default}{mean}{mean.default}
\keyword{univar}{mean}
\begin{Description}\relax
Generic function for the (trimmed) arithmetic mean.
\end{Description}
\begin{Usage}
\begin{verbatim}
mean(x, ...)

## Default S3 method:
mean(x, trim = 0, na.rm = FALSE, ...)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{x}] An \R{} object.  Currently there are methods for numeric data
frames, numeric vectors and dates.  A complex vector is allowed for
\code{trim = 0}, only.
\item[\code{trim}] the fraction (0 to 0.5) of observations to be
trimmed from each end of \code{x} before the mean is computed.
Values of trim outside that range are taken as the nearest endpoint.

\item[\code{na.rm}] a logical value indicating whether \code{NA}
values should be stripped before the computation proceeds.
\item[\code{...}] further arguments passed to or from other methods.
\end{ldescription}
\end{Arguments}
\begin{Value}
For a data frame, a named vector with the appropriate method being
applied column by column.

If \code{trim} is zero (the default),
the arithmetic mean of the values in \code{x} is computed, as a
numeric or complex vector of length one.  If \code{x} is
not logical (coerced to numeric), integer, numeric or complex,
\code{NA} is returned, with a warning.

If \code{trim} is non-zero, a symmetrically trimmed mean is computed
with a fraction of \code{trim} observations deleted from each end
before the mean is computed.
\end{Value}
\begin{References}\relax
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
\emph{The New S Language}.
Wadsworth \& Brooks/Cole.
\end{References}
\begin{SeeAlso}\relax
\code{\LinkA{weighted.mean}{weighted.mean}}, \code{\LinkA{mean.POSIXct}{mean.POSIXct}},
\code{\LinkA{colMeans}{colMeans}} for row and column means.
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
x <- c(0:10, 50)
xm <- mean(x)
c(xm, mean(x, trim = 0.10))

mean(USArrests, trim = 0.2)
\end{ExampleCode}
\end{Examples}

