| % File src/library/stats/man/weighted.mean.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2014 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{weighted.mean} |
| \alias{weighted.mean} |
| \alias{weighted.mean.default} |
| \title{Weighted Arithmetic Mean} |
| \description{ |
| Compute a weighted mean. |
| } |
| \usage{ |
| weighted.mean(x, w, \dots) |
| |
| \method{weighted.mean}{default}(x, w, \dots, na.rm = FALSE) |
| } |
| \arguments{ |
| \item{x}{an object containing the values whose weighted mean is to be |
| computed.} |
| \item{w}{a numerical vector of weights the same length as \code{x} giving |
| the weights to use for elements of \code{x}.} |
| \item{\dots}{arguments to be passed to or from methods.} |
| \item{na.rm}{a logical value indicating whether \code{NA} |
| values in \code{x} should be stripped before the computation proceeds.} |
| } |
| \details{ |
| This is a generic function and methods can be defined for the first |
| argument \code{x}: apart from the default methods there are methods |
| for the date-time classes \code{"POSIXct"}, \code{"POSIXlt"}, |
| \code{"difftime"} and \code{"Date"}. The default method will work for |
| any numeric-like object for which \code{[}, multiplication, division |
| and \code{\link{sum}} have suitable methods, including complex vectors. |
| |
| If \code{w} is missing then all elements of \code{x} are given the |
| same weight, otherwise the weights |
| are normalized to sum to one (if possible: if |
| their sum is zero or infinite the value is likely to be \code{NaN}). |
| |
| Missing values in \code{w} are not handled specially and so give a |
| missing value as the result. However, zero weights \emph{are} handled |
| specially and the corresponding \code{x} values are omitted from the |
| sum. |
| } |
| \value{ |
| For the default method, a length-one numeric vector. |
| } |
| \seealso{ |
| \code{\link{mean}} |
| } |
| \examples{ |
| ## GPA from Siegel 1994 |
| wt <- c(5, 5, 4, 1)/15 |
| x <- c(3.7,3.3,3.5,2.8) |
| xm <- weighted.mean(x, wt) |
| } |
| \keyword{univar} |