Non-parametric zero replacement strategies {Compositional}

Non-parametric zero replacement strategies

Description

Non-parametric zero replacement strategies.

Usage

zeroreplace(x, a = 0.65, delta = NULL, type = "multiplicative")

Arguments

x

A matrix with the compositional data.

a

The replacement value (\delta) will be "a" times the minimum value observed in the compositional data.

delta

Unless you specify the replacement value \delta here.

type

This can be any of "multiplicative", "additive" or "simple". See the references for more details.

Details

The "additive" is the zero replacement strategy suggested in Aitchison (1986, pg. 269). All of the three strategies can be found in Martin-Fernandez et al. (2003).

Value

A matrix with the zero replaced compositional data.

Author(s)

Michail Tsagris.

R implementation and documentation: Michail Tsagris [e-mail].

References

Martin-Fernandez J. A., Barcelo-Vidal C. & Pawlowsky-Glahn, V. (2003). Dealing with zeros and missing values in compositional data sets using nonparametric imputation. Mathematical Geology, 35(3): 253-278.

Aitchison J. (1986). The statistical analysis of compositional data. Chapman & Hall.

See Also

perturbation, alfa

Examples

x <- as.matrix(iris[1:20, 1:4])
x <- x/ rowSums(x)
x[ sample(1:20, 4),  sample(1:4, 1) ] <- 0
x <- x / rowSums(x)
zeroreplace(x)