coded.data {rsm}R Documentation

Functions for coded data

Description

These functions facilitate the use of coded data in response-surface analysis.

Usage

coded.data(data, ..., formulas = list(...))
as.coded.data(data, ..., formulas = list(...))
decode.data(data)
val2code(X, codings)
code2val(X, codings)
## S3 method for class 'coded.data':
print(x, ...)
parse.coding(form)

Arguments

data A data.frame
... Formulas of the form x ~ (var - ctr) / scal, where x is the name of the coded variable, var is the name of the variable on its original scale, ctr is the value to be coded as x = 0, and scal is the distance to 1 on the coded scale. These formulas should be separated by commas.
formulas Provides an alternative way to provide the coding formulas. This is useful if you want to retrieve the codings from one dataset and use them for another.
X A vector, matrix, or data.frame to be coded or decoded.
codings a list of formulas (see form)
x Coded dataset to be printet.
form A formula as described above for ...

Value

coded.data and as.coded.data return an object of class coded.data, which inherits from data.frame. print.coded.data is the print method for this class; it simply prints the data.frame and then the formulas. A named list of the coding formulas is saved in attr(, "codings").
Use coded.data to convert a data.frame in which the variables are on their original scales. The variables named in the formulas are coded and replaced with their coded versions (and also renamed). In contrast, as.coded.data does not modify any of the data; it assumes the variables are already coded, and the coding information is simply added.
decode.data converts a dataset of class coded.data and returns data.frame containing the original variables.
code2val converts coded values to the original scale using the codings provided, and returns an object of the same class as X. val2code converts the other direction. When using these functions, it is essential that the names (or column names in the case of matrices) match those of the corresponding coded or uncoded variables.
parse.coding is mostly for internal use; it extracts and returns a list with two vectors: a character vector names with the two variable names, and a numeric vector with the center and divisor.

Author(s)

Russell V. Lenth

See Also

data.frame

Examples

library(rsm)

CR = coded.data (ChemReact, x1~(Time-85)/5, x2~(Temp-175)/5)
CR
decode.data (CR)  ### will be same as ChemReact

code2val (c(x1=.5, x2=-1), codings = attr(CR, "codings"))

[Package rsm version 1.01 Index]