R: Transformation and standardization

prepare {VIM}

R Documentation

Transformation and standardization

Description

This function is used by the VIM GUI for transformation and standardization of the data.

Usage

  prepare (x, scaling =
    c("none","classical","MCD","robust","onestep"),
    transformation =
    c("none","minus","reciprocal","logarithm",
    "exponential","boxcox","clr","ilr","alr"), alpha =
    NULL, powers = NULL, start = 0, alrVar)

Arguments

`x`	a vector, matrix or `data.frame`.
`scaling`	the scaling to be applied to the data. Possible values are `"none"`, `"classical"`, `MCD`, `"robust"` and `"onestep"`.
`transformation`	the transformation of the data. Possible values are `"none"`, `"minus"`, `"reciprocal"`, `"logarithm"`, `"exponential"`, `"boxcox"`, `"clr"`, `"ilr"` and `"alr"`.
`alpha`	a numeric parameter controlling the size of the subset for the MCD (if `scaling="MCD"`). See `covMcd`.
`powers`	a numeric vector giving the powers to be used in the Box-Cox transformation (if `transformation="boxcox"`). If `NULL`, the powers are calculated with function `powerTransform`.
`start`	a constant to be added prior to Box-Cox transformation (if `transformation="boxcox"`).
`alrVar`	variable to be used as denominator in the additive logratio transformation (if `transformation="alr"`).

Details

Transformation:

"none": no transformation is used.

"logarithm": compute the the logarithm (to the base 10).

"boxcox": apply a Box-Cox transformation. Powers may be specified or calculated with the function powerTransform.

Standardization:

"none": no standardization is used.

"classical": apply a z-Transformation on each variable by using function scale.

"robust": apply a robustified z-Transformation by using median and MAD.

Value

Transformed and standardized data.

Author(s)

Matthias Templ, modifications by Andreas Alfons

Examples

data(sleep, package = "VIM")
x <- sleep[, c("BodyWgt", "BrainWgt")]
prepare(x, scaling = "robust", transformation = "logarithm")

[Package VIM version 4.0.0 Index]