matrixStats (version 0.12.2)

rowWeightedMeans.matrix: Calculates the weighted means for each row (column) in a matrix

Description

Calculates the weighted means for each row (column) in a matrix.

Usage

## S3 method for class 'matrix':
rowWeightedMeans(x, w=NULL, na.rm=FALSE, ...)
 ## S3 method for class 'matrix':
colWeightedMeans(x, w=NULL, na.rm=FALSE, ...)

Arguments

x

A numeric NxK matrix.

w

A numeric vector of length K (N).

na.rm

If TRUE, missing values are excluded from the calculation, otherwise not.

...

Not used.

Value

• Returns a numeric vector of length N (K).

Details

The implementations of these methods are optimized for both speed and memory. If no weights are given, the corresponding rowMeans()/colMeans() is used.

See Also

See rowMeans() and colMeans() in colSums() for non-weighted means. See also weighted.mean.

Examples

x <- matrix(rnorm(20), nrow=5, ncol=4)
print(x)

# Non-weighted row averages
xM0 <- rowMeans(x)
xM <- rowWeightedMeans(x)
stopifnot(all.equal(xM, xM0))

# Weighted row averages (uniform weights)
w <- rep(2.5, ncol(x))
xM <- rowWeightedMeans(x, w=w)
stopifnot(all.equal(xM, xM0))

# Weighted row averages (excluding some columns)
w <- c(1,1,0,1)
xM0 <- rowMeans(x[,(w == 1),drop=FALSE]);
xM <- rowWeightedMeans(x, w=w)
stopifnot(all.equal(xM, xM0))

# Weighted row averages (excluding some columns)
w <- c(0,1,0,0)
xM0 <- rowMeans(x[,(w == 1),drop=FALSE]);
xM <- rowWeightedMeans(x, w=w)
stopifnot(all.equal(xM, xM0))

# Weighted averages by rows and columns
w <- 1:4
xM1 <- rowWeightedMeans(x, w=w)
xM2 <- colWeightedMeans(t(x), w=w)
stopifnot(all.equal(xM2, xM1))