mean {base}  R Documentation 
Generic function for the (trimmed) arithmetic mean.
mean(x, ...) ## Default S3 method: mean(x, trim = 0, na.rm = FALSE, ...)
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.
Values outside that range are taken as the nearest endpoint.

na.rm 
a logical value indicating whether NA
values should be stripped before the computation proceeds. 
... 
further arguments passed to or from other methods. 
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 x
is
not logical (coerced to numeric), integer, numeric or complex,
NA
is returned, with a warning.
If trim
is nonzero, a symmetrically trimmed mean is computed
with a fraction of trim
observations deleted from each end
before the mean is computed.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
x < c(0:10, 50) xm < mean(x) c(xm, mean(x, trim = 0.10)) mean(USArrests, trim = 0.2)