R: Mediancenter

mediancenter {fastmatrix} | R Documentation

## Mediancenter

### Description

It calculates the mediancenter (or geometric median) of multivariate data.

### Usage

    mediancenter(x)

### Arguments

`x` | a matrix or data frame. As usual, rows are observations and columns are variables.

### Details

The mediancenter for a sample of multivariate observations is computed using a steepest descend method combined with bisection. The mediancenter invariant to rotations of axes and is useful as a multivariate generalization of the median of univariate sample.

### Value

A list containing the following named components:

`median` | an estimate for the mediancenter of the data.
`iter` | the number of iterations performed, it is negative if a degenerate solution is found.

### References

Gower, J.C. (1974). Algorithm AS 78: The mediancentre. Applied Statistics 23, 466-470.

### See Also

`cov.wt`, `median`.

### Examples

    x <- cbind(1:10, c(1:3, 8:5, 8:10))
    z <- mediancenter(x)$median # degenerate solution
    xbar <- colMeans(x)
    plot(x, xlab = "", ylab = "")
    points(x = xbar[1], y = xbar[2], pch = 16, col = "red")
    points(x = z[1], y = z[2], pch = 3, col = "blue", lwd = 2)

[Package fastmatrix version 0.4-1 Index]