R: Calculate Convex Hull Peeling Depth

depth.qhpeeling {ddalpha} | R Documentation

## Calculate Convex Hull Peeling Depth

### Description

Calculates the convex hull peeling depth of points w.r.t. a multivariate data set.

### Usage

    depth.qhpeeling(x, data)

### Arguments

`x` | Matrix of objects (numerical vector as one object) whose depth is to be calculated; each row contains a d-variate point. Should have the same dimension as `data`.
`data` | Matrix of data where each row contains a d-variate point, w.r.t. which the depth is to be calculated.

### Details

Calculates the convex hull peeling depth (Eddy, 1982; see also Cascos, 2009).

### Value

Numerical vector of depths, one for each row in `x`; or one depth value if `x` is a numerical vector. Each depth value equals the number of the convex hulls to be peeled from `data` so that (the corresponding row of) `x` is not contained in the convex hull of the rest of the data; the depths are normalized by the number of points in `data`.

### References

Eddy, W.F. (1982). Convex hull peeling. In: Caussinus, H., Ettinger, P. and Tomassone, R. (eds), COMPSTAT 1982. Proceedings in computational statistics, Physica-Verlag (Vienna), 42–47.

Cascos, I. (2009). Data depth: multivariate statistics and geometry. In: Kendall, W.S. and Molchanov, I. (eds) New Perspectives in Stochastic Geometry, Clarendon/Oxford University Press (Oxford).

### See Also

`depth.halfspace` for calculation of the Tukey depth.

`depth.L2` for calculation of L2-depth.

`depth.Mahalanobis` for calculation of Mahalanobis depth.

`depth.projection` for calculation of projection depth.

`depth.simplicial` for calculation of simplicial depth.

`depth.simplicialVolume` for calculation of simplicial volume depth.

`depth.spatial` for calculation of spatial depth.

`depth.potential` for calculation of data potential.

`depth.zonoid` for calculation of zonoid depth.

### Examples

    # Mixture of 3-variate normal distributions
    data <- mvrnorm(25, rep(0, 3), diag(3))
    x <- rbind(mvrnorm(10, rep(1, 3), diag(3)), data)
    depths <- depth.qhpeeling(x, data)
    cat("Depths:", depths, "\n")

[Package ddalpha version 1.3.11 Index]