mean                  package:base                  R Documentation

Arithmetic Mean

Description:

     Generic function for the (trimmed) arithmetic mean.

Usage:

     mean(x, ...)

     ## Default S3 method:
     mean(x, trim = 0, na.rm = FALSE, ...)

Arguments:

       x: An R object.  Currently there are methods for numeric data
          frames, numeric vectors and dates.  A complex vector is
          allowed for 'trim = 0', only.

    trim: the fraction (0 to 0.5) of observations to be trimmed from
          each end of 'x' before the mean is computed.

   na.rm: a logical value indicating whether 'NA' values should be
          stripped before the computation proceeds.

     ...: further arguments passed to or from other methods.

Value:

     For a data frame, a named vector with the appropriate method being
     applied column by column.

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

     If 'trim' is non-zero, a symmetrically trimmed mean is computed
     with a fraction of 'trim' observations deleted from each end
     before the mean is computed.

References:

     Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) _The New S
     Language_. Wadsworth & Brooks/Cole.

See Also:

     'weighted.mean', 'mean.POSIXct'

Examples:

     x <- c(0:10, 50)
     xm <- mean(x)
     c(xm, mean(x, trim = 0.10))

     mean(USArrests, trim = 0.2)

