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weighted.mean {stats}

Weighted Arithmetic Mean
Package: 
stats
Version: 
R 2.15.3

Description

Compute a weighted mean.

Usage

weighted.mean(x, w, ...)
 
## S3 method for class 'default':
weighted.mean((x, w, ..., na.rm = FALSE))

Arguments

x
an object containing the values whose weighted mean is to be computed.
w
a numerical vector of weights the same length as x giving the weights to use for elements of x.
...
arguments to be passed to or from methods.
na.rm
a logical value indicating whether NA values in x should be stripped before the computation proceeds.

Details

This is a generic function and methods can be defined for the first argument x: apart from the default methods there are methods for the date-time classes "POSIXct", "POSIXlt", "difftime" and "Date". The default method will work for any numeric-like object for which [, multiplication, division and sum have suitable methods, including complex vectors.

If w is missing then all elements of x are given the same weight, otherwise the weights coerced to numeric by as.numeric and normalized to sum to one (if possible: if their sum is zero or infinite the value is likely to be NaN).

Missing values in w are not handled specially and so give a missing value as the result. However, as from R 2.11.0 zero weights are handled specially and the corresponding x values are omitted from the sum.

Values

For the default method, a length-one numeric vector.

See Also

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)

Documentation reproduced from R 2.15.3. License: GPL-2.