weighted.mean {stats} | R Documentation |
Compute a weighted mean.
weighted.mean(x, w, ...)
## Default S3 method:
weighted.mean(x, w, ..., na.rm = FALSE)
x |
an object containing the values whose weighted mean is to be computed. |
w |
a numerical vector of weights the same length as |
... |
arguments to be passed to or from methods. |
na.rm |
a logical value indicating whether |
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
are 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, zero weights are handled
specially and the corresponding x
values are omitted from the
sum.
For the default method, a length-one numeric vector.
## 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)