doBy (version 4.5.1)

scaleBy: Groupwise scaling and centering of numeric columns in a dataframe

Description

Groupwise scaling and centering of numeric columns in a dataframe

Usage

scaleBy(formula, data, center = TRUE, scale. = TRUE)

Arguments

formula

A formula. A dot (.) is allowed on both left and right hand side of formula. See 'details' for the meaning of this.

data

A dataframe

center

If TRUE then data is centered to have mean zero

scale.

If TRUE then data is scaled to have variance one

Value

• A dataframe

Details

A typical formula is y1+y2~f1+f2 where y1 and y2 are numeric variables and f1 and f2 can be of any type. For each cross-combination of the values of f1 and f2, the variables (y1,y2) are centered/scaled. It is valid to write .~f1+f2. In this case the variables to be centered/scaled are taken to be all numeric variables in the dataframe except those that a listed on the right hand side of the formula. It is valid to write y1+y2~.. In this case the stratification is taken to be by all non-numeric variables. If there are no non-numeric variables, then no stratification is made and a 'global' centering/scaling is made. It is valid to write .~.. In this case the variables to be centered/scaled are taken to be all numeric variables in the dataframe. The stratification is made by all non-numeric variables. If there are no non-numeric variables, then no stratification is made and a 'global' centering/scaling is made.

See Also

lapplyBy, orderBy, splitBy, summaryBy, transformBy,

Examples

data(dietox)

# "Remove" the effect of time by centering data within each time point.
dietox2 <- scaleBy(Weight~Time, data=dietox, scale=FALSE)

library(lattice)
xyplot(Weight~Time|Evit+Cu, groups=Pig, data=dietox)
xyplot(Weight~Time|Evit+Cu, groups=Pig, data=dietox2)